Server System Variables

The MariaDB server maintains many system variables that indicate how it is configured. Each system variable has a default value. System variables can be set at server startup using options on the command line or in an option file. Most of them can be changed dynamically while the server is running by means of the SET statement, which enables you to modify operation of the server without having to stop and restart it. You can refer to system variable values in expressions.

There are several ways to see the names and values of system variables:

To see the values that a server will use based on its compiled-in defaults and any option files that it reads, use this command:
```
mysqld --verbose --help
```
To see the values that a server will use based on its compiled-in defaults, ignoring the settings in any option files, use this command:
```
mysqld --no-defaults --verbose --help
```
To see the current values used by a running server, use the SHOW VARIABLES statement.

This section provides a description of each system variable. Variables with no version indicated are present in all MariaDB 5.6 releases. For historical information concerning their implementation, please see http://dev.mysql.com/doc/refman/5.0/en/, and http://dev.mysql.com/doc/refman/4.1/en/.

The following table lists all available system variables:

Table 5.2. System Variable Summary

Name	Cmd-Line	Option file	System Var	Var Scope	Dynamic
auto_increment_increment	Yes	Yes	Yes	Both	Yes
auto_increment_offset	Yes	Yes	Yes	Both	Yes
autocommit	Yes	Yes	Yes	Both	Yes
automatic_sp_privileges			Yes	Global	Yes
back_log	Yes	Yes	Yes	Global	No
basedir	Yes	Yes	Yes	Global	No
big-tables	Yes	Yes			Yes
- Variable: big_tables			Yes	Both	Yes
bind-address	Yes	Yes	Yes	Global	No
binlog_cache_size	Yes	Yes	Yes	Global	Yes
binlog_checksum			Yes	Global	Yes
binlog_direct_non_transactional_updates	Yes	Yes	Yes	Both	Yes
binlog-format	Yes	Yes			Yes
- Variable: binlog_format			Yes	Both	Yes
binlog_row_image	Yes		Yes	Both	Yes
binlog_stmt_cache_size	Yes	Yes	Yes	Global	Yes
bulk_insert_buffer_size	Yes	Yes	Yes	Both	Yes
character_set_client			Yes	Both	Yes
character_set_connection			Yes	Both	Yes
character_set_database^[a]			Yes	Both	Yes
character-set-filesystem	Yes	Yes			Yes
- Variable: character_set_filesystem			Yes	Both	Yes
character_set_results			Yes	Both	Yes
character-set-server	Yes	Yes			Yes
- Variable: character_set_server			Yes	Both	Yes
character_set_system			Yes	Global	No
character-sets-dir	Yes	Yes			No
- Variable: character_sets_dir			Yes	Global	No
collation_connection			Yes	Both	Yes
collation_database^[b]			Yes	Both	Yes
collation-server	Yes	Yes			Yes
- Variable: collation_server			Yes	Both	Yes
completion_type	Yes	Yes	Yes	Both	Yes
concurrent_insert	Yes	Yes	Yes	Global	Yes
connect_timeout	Yes	Yes	Yes	Global	Yes
datadir	Yes	Yes	Yes	Global	No
date_format			Yes	Global	No
datetime_format			Yes	Global	No
debug	Yes	Yes	Yes	Both	Yes
debug_sync			Yes	Session	Yes
default-storage-engine	Yes	Yes			Yes
- Variable: default_storage_engine			Yes	Both	Yes
default_tmp_storage_engine	Yes	Yes	Yes	Both	Yes
default_week_format	Yes	Yes	Yes	Both	Yes
delay-key-write	Yes	Yes			Yes
- Variable: delay_key_write			Yes	Global	Yes
delayed_insert_limit	Yes	Yes	Yes	Global	Yes
delayed_insert_timeout	Yes	Yes	Yes	Global	Yes
delayed_queue_size	Yes	Yes	Yes	Global	Yes
div_precision_increment	Yes	Yes	Yes	Both	Yes
end_markers_in_json			Yes	Both	Yes
engine-condition-pushdown	Yes	Yes			Yes
- Variable: engine_condition_pushdown			Yes	Both	Yes
eq_range_index_dive_limit	Yes	Yes	Yes	Both	Yes
error_count			Yes	Session	No
event-scheduler	Yes	Yes			Yes
- Variable: event_scheduler			Yes	Global	Yes
expire_logs_days	Yes	Yes	Yes	Global	Yes
external_user			Yes	Session	No
flush	Yes	Yes	Yes	Global	Yes
flush_time	Yes	Yes	Yes	Global	Yes
foreign_key_checks			Yes	Both	Yes
ft_boolean_syntax	Yes	Yes	Yes	Global	Yes
ft_max_word_len	Yes	Yes	Yes	Global	No
ft_min_word_len	Yes	Yes	Yes	Global	No
ft_query_expansion_limit	Yes	Yes	Yes	Global	No
ft_stopword_file	Yes	Yes	Yes	Global	No
general-log	Yes	Yes			Yes
- Variable: general_log			Yes	Global	Yes
general_log_file	Yes	Yes	Yes	Global	Yes
group_concat_max_len	Yes	Yes	Yes	Both	Yes
have_compress			Yes	Global	No
have_crypt			Yes	Global	No
have_csv			Yes	Global	No
have_dynamic_loading			Yes	Global	No
have_geometry			Yes	Global	No
have_innodb			Yes	Global	No
have_ndbcluster			Yes	Global	No
have_openssl			Yes	Global	No
have_partitioning			Yes	Global	No
have_profiling			Yes	Global	No
have_query_cache			Yes	Global	No
have_rtree_keys			Yes	Global	No
have_ssl			Yes	Global	No
have_symlink			Yes	Global	No
host_cache_size	Yes	Yes	Yes	Global	Yes
hostname			Yes	Global	No
identity			Yes	Session	Yes
ignore-builtin-innodb	Yes	Yes			No
- Variable: ignore_builtin_innodb			Yes	Global	No
init_connect	Yes	Yes	Yes	Global	Yes
init-file	Yes	Yes			No
- Variable: init_file			Yes	Global	No
init_slave	Yes	Yes	Yes	Global	Yes
innodb_adaptive_flushing	Yes	Yes	Yes	Global	Yes
innodb_adaptive_hash_index	Yes	Yes	Yes	Global	Yes
innodb_adaptive_max_sleep_delay	Yes	Yes	Yes	Global	Yes
innodb_additional_mem_pool_size	Yes	Yes	Yes	Global	No
innodb_analyze_is_persistent	Yes	Yes	Yes	Global	Yes
innodb_autoextend_increment	Yes	Yes	Yes	Global	Yes
innodb_autoinc_lock_mode	Yes	Yes	Yes	Global	No
innodb_buffer_pool_dump_at_shutdown	Yes	Yes	Yes	Global	Yes
innodb_buffer_pool_dump_now	Yes	Yes	Yes	Global	Yes
innodb_buffer_pool_filename	Yes	Yes	Yes	Global	Yes
innodb_buffer_pool_instances	Yes	Yes	Yes	Global	No
innodb_buffer_pool_load_abort	Yes	Yes	Yes	Global	Yes
innodb_buffer_pool_load_at_startup	Yes	Yes	Yes	Global	Yes
innodb_buffer_pool_load_now	Yes	Yes	Yes	Global	Yes
innodb_buffer_pool_size	Yes	Yes	Yes	Global	No
innodb_change_buffer_max_size	Yes	Yes	Yes	Global	Yes
innodb_change_buffering	Yes	Yes	Yes	Global	Yes
innodb_checksum_algorithm	Yes	Yes	Yes	Global	Yes
innodb_checksums	Yes	Yes	Yes	Global	No
innodb_commit_concurrency	Yes	Yes	Yes	Global	Yes
innodb_concurrency_tickets	Yes	Yes	Yes	Global	Yes
innodb_data_file_path	Yes	Yes	Yes	Global	No
innodb_data_home_dir	Yes	Yes	Yes	Global	No
innodb_doublewrite	Yes	Yes	Yes	Global	No
innodb_fast_shutdown	Yes	Yes	Yes	Global	Yes
innodb_file_format	Yes	Yes	Yes	Global	Yes
innodb_file_format_check	Yes	Yes	Yes	Global	No
innodb_file_format_max	Yes	Yes	Yes	Global	Yes
innodb_file_per_table	Yes	Yes	Yes	Global	Yes
innodb_flush_log_at_trx_commit	Yes	Yes	Yes	Global	Yes
innodb_flush_method	Yes	Yes	Yes	Global	No
innodb_flush_neighbors	Yes	Yes	Yes	Global	Yes
innodb_force_load_corrupted	Yes	Yes	Yes	Global	No
innodb_force_recovery	Yes	Yes	Yes	Global	No
innodb_ft_aux_table	Yes	Yes	Yes	Global	Yes
innodb_ft_cache_size	Yes	Yes	Yes	Global	Yes
innodb_ft_enable_stopword	Yes	Yes	Yes	Global	Yes
innodb_ft_max_token_size	Yes	Yes	Yes	Global	Yes
innodb_ft_min_token_size	Yes	Yes	Yes	Global	Yes
innodb_ft_num_word_optimize	Yes	Yes	Yes	Global	Yes
innodb_ft_server_stopword_table	Yes	Yes	Yes	Global	Yes
innodb_ft_sort_pll_degree	Yes	Yes	Yes	Global	Yes
innodb_ft_user_stopword_table	Yes	Yes	Yes	Global	Yes
innodb_io_capacity	Yes	Yes	Yes	Global	Yes
innodb_large_prefix	Yes	Yes	Yes	Global	Yes
innodb_lock_wait_timeout	Yes	Yes	Yes	Both	Yes
innodb_locks_unsafe_for_binlog	Yes	Yes	Yes	Global	No
innodb_log_buffer_size	Yes	Yes	Yes	Global	No
innodb_log_file_size	Yes	Yes	Yes	Global	No
innodb_log_files_in_group	Yes	Yes	Yes	Global	No
innodb_log_group_home_dir	Yes	Yes	Yes	Global	No
innodb_lru_scan_depth	Yes	Yes	Yes	Global	Yes
innodb_max_dirty_pages_pct	Yes	Yes	Yes	Global	Yes
innodb_max_purge_lag	Yes	Yes	Yes	Global	Yes
innodb_mirrored_log_groups	Yes	Yes	Yes	Global	No
innodb_monitor_disable	Yes	Yes	Yes	Global	Yes
innodb_monitor_enable	Yes	Yes	Yes	Global	Yes
innodb_monitor_reset	Yes	Yes	Yes	Global	Yes
innodb_monitor_reset_all	Yes	Yes	Yes	Global	Yes
innodb_old_blocks_pct	Yes	Yes	Yes	Global	Yes
innodb_old_blocks_time	Yes	Yes	Yes	Global	Yes
innodb_open_files	Yes	Yes	Yes	Global	No
innodb_optimize_fulltext_only	Yes	Yes	Yes	Global	Yes
innodb_page_size	Yes	Yes	Yes	Global	No
innodb_print_all_deadlocks	Yes	Yes	Yes	Global	Yes
innodb_purge_batch_size	Yes	Yes	Yes	Global	No
innodb_purge_threads	Yes	Yes	Yes	Global	No
innodb_random_read_ahead	Yes	Yes	Yes	Global	Yes
innodb_read_ahead_threshold	Yes	Yes	Yes	Global	Yes
innodb_read_io_threads	Yes	Yes	Yes	Global	No
innodb_replication_delay	Yes	Yes	Yes	Global	Yes
innodb_rollback_on_timeout	Yes	Yes	Yes	Global	No
innodb_rollback_segments	Yes	Yes	Yes	Global	Yes
innodb_sort_buffer_size	Yes	Yes	Yes	Global	Yes
innodb_spin_wait_delay	Yes	Yes	Yes	Global	Yes
innodb_stats_method	Yes	Yes	Yes	Both	Yes
innodb_stats_on_metadata	Yes	Yes	Yes	Global	Yes
innodb_stats_persistent_sample_pages	Yes	Yes	Yes	Global	Yes
innodb_stats_sample_pages	Yes	Yes	Yes	Global	Yes
innodb_stats_transient_sample_pages	Yes	Yes	Yes	Global	Yes
innodb_strict_mode	Yes	Yes	Yes	Both	Yes
innodb_support_xa	Yes	Yes	Yes	Both	Yes
innodb_sync_array_size	Yes	Yes	Yes	Global	No
innodb_sync_spin_loops	Yes	Yes	Yes	Global	Yes
innodb_table_locks	Yes	Yes	Yes	Both	Yes
innodb_thread_concurrency	Yes	Yes	Yes	Global	Yes
innodb_thread_sleep_delay	Yes	Yes	Yes	Global	Yes
innodb_undo_directory	Yes	Yes	Yes	Global	Yes
innodb_undo_logs	Yes	Yes	Yes	Global	Yes
innodb_undo_tablespaces	Yes	Yes	Yes	Global	Yes
innodb_use_native_aio	Yes	Yes	Yes	Global	No
innodb_use_sys_malloc	Yes	Yes	Yes	Global	No
innodb_version			Yes	Global	No
innodb_write_io_threads	Yes	Yes	Yes	Global	No
insert_id			Yes	Session	Yes
interactive_timeout	Yes	Yes	Yes	Both	Yes
join_buffer_size	Yes	Yes	Yes	Both	Yes
keep_files_on_create	Yes	Yes	Yes	Both	Yes
key_buffer_size	Yes	Yes	Yes	Global	Yes
key_cache_age_threshold	Yes	Yes	Yes	Global	Yes
key_cache_block_size	Yes	Yes	Yes	Global	Yes
key_cache_division_limit	Yes	Yes	Yes	Global	Yes
language	Yes	Yes	Yes	Global	No
large_files_support			Yes	Global	No
large_page_size			Yes	Global	No
large-pages	Yes	Yes			No
- Variable: large_pages			Yes	Global	No
last_insert_id			Yes	Session	Yes
lc-messages	Yes	Yes			Yes
- Variable: lc_messages			Yes	Both	Yes
lc-messages-dir	Yes	Yes			No
- Variable: lc_messages_dir			Yes	Global	No
lc_time_names			Yes	Both	Yes
license			Yes	Global	No
local_infile			Yes	Global	Yes
lock_wait_timeout	Yes	Yes	Yes	Both	Yes
locked_in_memory			Yes	Global	No
log	Yes	Yes	Yes	Global	Yes
log_bin			Yes	Global	No
log-bin	Yes	Yes	Yes	Global	No
log_bin_basename			Yes	Global	No
log-error	Yes	Yes			No
- Variable: log_error			Yes	Global	No
log-output	Yes	Yes			Yes
- Variable: log_output			Yes	Global	Yes
log-queries-not-using-indexes	Yes	Yes			Yes
- Variable: log_queries_not_using_indexes			Yes	Global	Yes
log-slave-updates	Yes	Yes			No
- Variable: log_slave_updates			Yes	Global	No
log-slow-queries	Yes	Yes			Yes
- Variable: log_slow_queries			Yes	Global	Yes
log_throttle_queries_not_using_indexes			Yes	Global	Yes
log-warnings	Yes	Yes			Yes
- Variable: log_warnings			Yes	Global	Yes
long_query_time	Yes	Yes	Yes	Both	Yes
low-priority-updates	Yes	Yes			Yes
- Variable: low_priority_updates			Yes	Both	Yes
lower_case_file_system	Yes	Yes	Yes	Global	No
lower_case_table_names	Yes	Yes	Yes	Global	No
master_info_repository			Yes	Global	No
master_verify_checksum			Yes	Global	Yes
max_allowed_packet	Yes	Yes	Yes	Global	Yes
max_binlog_cache_size	Yes	Yes	Yes	Global	Yes
max_binlog_size	Yes	Yes	Yes	Global	Yes
max_binlog_stmt_cache_size	Yes	Yes	Yes	Global	Yes
max_connect_errors	Yes	Yes	Yes	Global	Yes
max_connections	Yes	Yes	Yes	Global	Yes
max_delayed_threads	Yes	Yes	Yes	Both	Yes
max_error_count	Yes	Yes	Yes	Both	Yes
max_heap_table_size	Yes	Yes	Yes	Both	Yes
max_insert_delayed_threads			Yes	Both	Yes
max_join_size	Yes	Yes	Yes	Both	Yes
max_length_for_sort_data	Yes	Yes	Yes	Both	Yes
max_prepared_stmt_count	Yes	Yes	Yes	Global	Yes
max_relay_log_size	Yes	Yes	Yes	Global	Yes
max_seeks_for_key	Yes	Yes	Yes	Both	Yes
max_sort_length	Yes	Yes	Yes	Both	Yes
max_sp_recursion_depth	Yes	Yes	Yes	Both	Yes
max_tmp_tables	Yes	Yes	Yes	Both	Yes
max_user_connections	Yes	Yes	Yes	Both	Yes
max_write_lock_count	Yes	Yes	Yes	Global	Yes
memlock	Yes	Yes	Yes	Global	No
metadata_locks_cache_size			Yes	Global	No
min-examined-row-limit	Yes	Yes	Yes	Both	Yes
myisam_data_pointer_size	Yes	Yes	Yes	Global	Yes
myisam_max_sort_file_size	Yes	Yes	Yes	Global	Yes
myisam_mmap_size	Yes	Yes	Yes	Global	No
myisam_recover_options			Yes	Global	No
myisam_repair_threads	Yes	Yes	Yes	Both	Yes
myisam_sort_buffer_size	Yes	Yes	Yes	Both	Yes
myisam_stats_method	Yes	Yes	Yes	Both	Yes
myisam_use_mmap	Yes	Yes	Yes	Global	Yes
named_pipe			Yes	Global	No
net_buffer_length	Yes	Yes	Yes	Both	Yes
net_read_timeout	Yes	Yes	Yes	Both	Yes
net_retry_count	Yes	Yes	Yes	Both	Yes
net_write_timeout	Yes	Yes	Yes	Both	Yes
new	Yes	Yes	Yes	Both	Yes
old	Yes	Yes	Yes	Global	No
old-alter-table	Yes	Yes			Yes
- Variable: old_alter_table			Yes	Both	Yes
old-passwords	Yes	Yes			Yes
- Variable: old_passwords			Yes	Both	Yes
open-files-limit	Yes	Yes			No
- Variable: open_files_limit			Yes	Global	No
optimizer_join_cache_level	Yes	Yes	Yes	Both	Yes
optimizer_prune_level	Yes	Yes	Yes	Both	Yes
optimizer_search_depth	Yes	Yes	Yes	Both	Yes
optimizer_switch	Yes	Yes	Yes	Both	Yes
optimizer_trace			Yes	Both	Yes
optimizer_trace_features			Yes	Both	Yes
optimizer_trace_limit			Yes	Both	Yes
optimizer_trace_max_mem_size			Yes	Both	Yes
optimizer_trace_offset			Yes	Both	Yes
partition	Yes	Yes			No
- Variable: have_partitioning			Yes	Global	No
performance_schema	Yes	Yes	Yes	Global	No
performance_schema_accounts_size	Yes	Yes	Yes	Global	No
performance_schema_events_stages_history_long_size	Yes	Yes	Yes	Global	No
performance_schema_events_stages_history_size	Yes	Yes	Yes	Global	No
performance_schema_events_statements_history_long_size	Yes	Yes	Yes	Global	No
performance_schema_events_statements_history_size	Yes	Yes	Yes	Global	No
performance_schema_events_waits_history_long_size	Yes	Yes	Yes	Global	No
performance_schema_events_waits_history_size	Yes	Yes	Yes	Global	No
performance_schema_hosts_size	Yes	Yes	Yes	Global	No
performance_schema_max_cond_classes	Yes	Yes	Yes	Global	No
performance_schema_max_cond_instances	Yes	Yes	Yes	Global	No
performance_schema_max_file_classes	Yes	Yes	Yes	Global	No
performance_schema_max_file_handles	Yes	Yes	Yes	Global	No
performance_schema_max_file_instances	Yes	Yes	Yes	Global	No
performance_schema_max_mutex_classes	Yes	Yes	Yes	Global	No
performance_schema_max_mutex_instances	Yes	Yes	Yes	Global	No
performance_schema_max_rwlock_classes	Yes	Yes	Yes	Global	No
performance_schema_max_rwlock_instances	Yes	Yes	Yes	Global	No
performance_schema_max_socket_classes	Yes	Yes	Yes	Global	No
performance_schema_max_socket_instances	Yes	Yes	Yes	Global	No
performance_schema_max_stage_classes	Yes	Yes	Yes	Global	No
performance_schema_max_statement_classes	Yes	Yes	Yes	Global	No
performance_schema_max_table_handles	Yes	Yes	Yes	Global	No
performance_schema_max_table_instances	Yes	Yes	Yes	Global	No
performance_schema_max_thread_classes	Yes	Yes	Yes	Global	No
performance_schema_max_thread_instances	Yes	Yes	Yes	Global	No
performance_schema_setup_actors_size	Yes	Yes	Yes	Global	No
performance_schema_setup_objects_size	Yes	Yes	Yes	Global	No
performance_schema_users_size	Yes	Yes	Yes	Global	No
pid-file	Yes	Yes			No
- Variable: pid_file			Yes	Global	No
plugin_dir	Yes	Yes	Yes	Global	No
port	Yes	Yes	Yes	Global	No
preload_buffer_size	Yes	Yes	Yes	Both	Yes
profiling			Yes	Both	Yes
profiling_history_size	Yes	Yes	Yes	Both	Yes
protocol_version			Yes	Global	No
proxy_user			Yes	Session	No
pseudo_thread_id			Yes	Session	Yes
query_alloc_block_size	Yes	Yes	Yes	Both	Yes
query_cache_limit	Yes	Yes	Yes	Global	Yes
query_cache_min_res_unit	Yes	Yes	Yes	Global	Yes
query_cache_size	Yes	Yes	Yes	Global	Yes
query_cache_type	Yes	Yes	Yes	Both	Yes
query_cache_wlock_invalidate	Yes	Yes	Yes	Both	Yes
query_prealloc_size	Yes	Yes	Yes	Both	Yes
rand_seed1			Yes	Session	Yes
rand_seed2			Yes	Session	Yes
range_alloc_block_size	Yes	Yes	Yes	Both	Yes
read_buffer_size	Yes	Yes	Yes	Both	Yes
read_only	Yes	Yes	Yes	Global	Yes
read_rnd_buffer_size	Yes	Yes	Yes	Both	Yes
relay_log_basename			Yes	Global	No
relay-log-index	Yes	Yes			No
- Variable: relay_log_index			Yes	Both	No
relay_log_index	Yes	Yes	Yes	Global	No
relay_log_info_file	Yes	Yes	Yes	Global	No
relay_log_info_repository			Yes	Global	No
relay_log_purge	Yes	Yes	Yes	Global	Yes
relay_log_recovery	Yes	Yes	Yes	Global	Yes
relay_log_space_limit	Yes	Yes	Yes	Global	No
report-host	Yes	Yes			No
- Variable: report_host			Yes	Global	No
report-password	Yes	Yes			No
- Variable: report_password			Yes	Global	No
report-port	Yes	Yes			No
- Variable: report_port			Yes	Global	No
report-user	Yes	Yes			No
- Variable: report_user			Yes	Global	No
rpl_semi_sync_master_enabled			Yes	Global	Yes
rpl_semi_sync_master_timeout			Yes	Global	Yes
rpl_semi_sync_master_trace_level			Yes	Global	Yes
rpl_semi_sync_master_wait_no_slave			Yes	Global	Yes
rpl_semi_sync_slave_enabled			Yes	Global	Yes
rpl_semi_sync_slave_trace_level			Yes	Global	Yes
secure-auth	Yes	Yes			Yes
- Variable: secure_auth			Yes	Global	Yes
secure-file-priv	Yes	Yes			No
- Variable: secure_file_priv			Yes	Global	No
server-id	Yes	Yes			Yes
- Variable: server_id			Yes	Global	Yes
server_uuid			Yes	Global	No
shared_memory			Yes	Global	No
shared_memory_base_name			Yes	Global	No
skip-external-locking	Yes	Yes			No
- Variable: skip_external_locking			Yes	Global	No
skip-name-resolve	Yes	Yes			No
- Variable: skip_name_resolve			Yes	Global	No
skip-networking	Yes	Yes			No
- Variable: skip_networking			Yes	Global	No
skip-show-database	Yes	Yes			No
- Variable: skip_show_database			Yes	Global	No
slave_compressed_protocol	Yes	Yes	Yes	Global	Yes
slave_exec_mode			Yes	Global	Yes
slave-load-tmpdir	Yes	Yes			No
- Variable: slave_load_tmpdir			Yes	Global	No
slave-net-timeout	Yes	Yes			Yes
- Variable: slave_net_timeout			Yes	Global	Yes
slave_parallel_workers			Yes	Global	Yes
slave-skip-errors	Yes	Yes			No
- Variable: slave_skip_errors			Yes	Global	No
slave_sql_verify_checksum			Yes	Global	Yes
slave_transaction_retries	Yes	Yes	Yes	Global	Yes
slave_type_conversions	Yes	Yes	Yes	Global	No
slow_launch_time	Yes	Yes	Yes	Global	Yes
slow-query-log	Yes	Yes			Yes
- Variable: slow_query_log			Yes	Global	Yes
slow_query_log_file	Yes	Yes	Yes	Global	Yes
socket	Yes	Yes	Yes	Global	No
sort_buffer_size	Yes	Yes	Yes	Both	Yes
sql_auto_is_null			Yes	Both	Yes
sql_big_selects			Yes	Both	Yes
sql_big_tables			Yes	Both	Yes
sql_buffer_result			Yes	Both	Yes
sql_log_bin			Yes	Both	Yes
sql_log_off			Yes	Both	Yes
sql_low_priority_updates			Yes	Both	Yes
sql_max_join_size			Yes	Both	Yes
sql-mode	Yes	Yes			Yes
- Variable: sql_mode			Yes	Both	Yes
sql_notes			Yes	Both	Yes
sql_quote_show_create			Yes	Both	Yes
sql_safe_updates			Yes	Both	Yes
sql_select_limit			Yes	Both	Yes
sql_slave_skip_counter			Yes	Global	Yes
sql_warnings			Yes	Both	Yes
ssl-ca	Yes	Yes			No
- Variable: ssl_ca			Yes	Global	No
ssl-capath	Yes	Yes			No
- Variable: ssl_capath			Yes	Global	No
ssl-cert	Yes	Yes			No
- Variable: ssl_cert			Yes	Global	No
ssl-cipher	Yes	Yes			No
- Variable: ssl_cipher			Yes	Global	No
ssl-crl	Yes	Yes			No
- Variable: ssl_crl			Yes	Global	No
ssl-crlpath	Yes	Yes			No
- Variable: ssl_crlpath			Yes	Global	No
ssl-key	Yes	Yes			No
- Variable: ssl_key			Yes	Global	No
storage_engine			Yes	Both	Yes
sync_binlog	Yes	Yes	Yes	Global	Yes
sync_frm	Yes	Yes	Yes	Global	Yes
sync_master_info	Yes	Yes	Yes	Global	Yes
sync_relay_log	Yes	Yes	Yes	Global	Yes
sync_relay_log_info	Yes	Yes	Yes	Global	Yes
system_time_zone			Yes	Global	No
table_definition_cache	Yes	Yes	Yes	Global	Yes
table_open_cache	Yes	Yes	Yes	Global	Yes
thread_cache_size	Yes	Yes	Yes	Global	Yes
thread_concurrency	Yes	Yes	Yes	Global	No
thread_handling	Yes	Yes	Yes	Global	No
thread_stack	Yes	Yes	Yes	Global	No
time_format			Yes	Global	No
time_zone	Yes	Yes	Yes	Both	Yes
timed_mutexes	Yes	Yes	Yes	Global	Yes
timestamp			Yes	Session	Yes
tmp_table_size	Yes	Yes	Yes	Both	Yes
tmpdir	Yes	Yes	Yes	Global	No
transaction_alloc_block_size	Yes	Yes	Yes	Both	Yes
transaction_prealloc_size	Yes	Yes	Yes	Both	Yes
tx_isolation			Yes	Both	Yes
tx_read_only			Yes	Both	Yes
unique_checks			Yes	Both	Yes
updatable_views_with_limit	Yes	Yes	Yes	Both	Yes
version			Yes	Global	No
version_comment			Yes	Global	No
version_compile_machine			Yes	Global	No
version_compile_os			Yes	Global	No
wait_timeout	Yes	Yes	Yes	Both	Yes
warning_count			Yes	Session	No
^[a] This option is dynamic, but only the server should set this information. You should not set the value of this variable manually. ^[b] This option is dynamic, but only the server should set this information. You should not set the value of this variable manually.

For additional system variable information, see these sections:

, "Using System Variables", discusses the syntax for setting and displaying system variable values.
, "Dynamic System Variables", lists the variables that can be set at runtime.
Information on tuning system variables can be found in , "Tuning Server Parameters".
, "InnoDB Startup Options and System Variables", lists InnoDB system variables.
MySQL Cluster System Variables, lists system variables which are specific to MariaDB Cluster.
For information on server system variables specific to replication, see , "Replication and Binary Logging Options and Variables".

Note

Some of the following variable descriptions refer to "enabling" or "disabling" a variable. These variables can be enabled with the SET statement by setting them to ON or 1, or disabled by setting them to OFF or 0. However, before MariaDB 5.6.2, to set such a variable on the command line or in an option file, you must set it to 1 or 0; setting it to ON or OFF will not work. For example, on the command line, --delay_key_write=1 works but --delay_key_write=ON does not. As of MariaDB 5.6.2, boolean variables can be set at startup to the values ON, TRUE, OFF, and FALSE (not case sensitive). See , "Program Option Modifiers".

Some system variables control the size of buffers or caches. For a given buffer, the server might need to allocate internal data structures. These structures typically are allocated from the total memory allocated to the buffer, and the amount of space required might be platform dependent. This means that when you assign a value to a system variable that controls a buffer size, the amount of space actually available might differ from the value assigned. In some cases, the amount might be less than the value assigned. It is also possible that the server will adjust a value upward. For example, if you assign a value of 0 to a variable for which the minimal value is 1024, the server will set the value to 1024.

Values for buffer sizes, lengths, and stack sizes are given in bytes unless otherwise specified.

Some system variables take file name values. Unless otherwise specified, the default file location is the data directory if the value is a relative path name. To specify the location explicitly, use an absolute path name. Suppose that the data directory is /var/mysql/data. If a file-valued variable is given as a relative path name, it will be located under /var/mysql/data. If the value is an absolute path name, its location is as given by the path name.

autocommit

Command-Line Format	`--autocommit[=#]`
Option-File Format	`autocommit`
Option Sets Variable	Yes, `autocommit`
Variable Name	`autocommit`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`

The autocommit mode. If set to 1, all changes to a table take effect immediately. If set to 0, you must use COMMIT to accept a transaction or ROLLBACK to cancel it. If autocommit is 0 and you change it to 1, MariaDB performs an automatic COMMIT of any open transaction. Another way to begin a transaction is to use a START TRANSACTION or BEGIN statement. See , "START TRANSACTION, COMMIT, and ROLLBACK Syntax".

By default, client connections begin with autocommit set to 1. To cause clients to begin with a default of 0, set the global autocommit value by starting the server with the --autocommit=0 option. To set the variable using an option file, include these lines:

[mysqld]
autocommit=0

automatic_sp_privileges

Variable Name automatic_sp_privileges
Variable Scope Global
Dynamic Variable Yes
Permitted Values
Type boolean
Default TRUE

When this variable has a value of 1 (the default), the server automatically grants the EXECUTE and ALTER ROUTINE privileges to the creator of a stored routine, if the user cannot already execute and alter or drop the routine. (The ALTER ROUTINE privilege is required to drop the routine.) The server also automatically drops those privileges from the creator when the routine is dropped. If automatic_sp_privileges is 0, the server does not automatically add or drop these privileges.
The creator of a routine is the account used to execute the CREATE statement for it. This might not be the same as the account named as the DEFINER in the routine definition.
See also , "Stored Routines and MariaDB Privileges".

back_log

Command-Line Format	`--back_log=#`
Option-File Format	`back_log`
Option Sets Variable	Yes, `back_log`
Variable Name	`back_log`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`numeric`
	Default	`50`
	Range	`1 .. 65535`

The number of outstanding connection requests MariaDB can have. This comes into play when the main MariaDB thread gets very many connection requests in a very short time. It then takes some time (although very little) for the main thread to check the connection and start a new thread. The back_log value indicates how many requests can be stacked during this short time before MariaDB momentarily stops answering new requests. You need to increase this only if you expect a large number of connections in a short period of time.

In other words, this value is the size of the listen queue for incoming TCP/IP connections. Your operating system has its own limit on the size of this queue. The manual page for the Unix listen() system call should have more details. Check your OS documentation for the maximum value for this variable. back_log cannot be set higher than your operating system limit.

basedir

Command-Line Format	`--basedir=path`
	`-b`
Option-File Format	`basedir`
Option Sets Variable	Yes, `basedir`
Variable Name	`basedir`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`file name`

The MariaDB installation base directory. This variable can be set with the --basedir option. Relative path names for other variables usually are resolved relative to the base directory.

big_tables
If set to 1, all temporary tables are stored on disk rather than in memory. This is a little slower, but the error The table tbl_name is full does not occur for SELECT operations that require a large temporary table. The default value for a new connection is 0 (use in-memory temporary tables). Normally, you should never need to set this variable, because in-memory tables are automatically converted to disk-based tables as required.

bind_address

Command-Line Format	`--bind-address=name`
Option-File Format	`bind-address=name`
Variable Name	`bind-address`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`string`
	Default	`0.0.0.0`
	Range	`255.255.255.255`

The value of the --bind-address option. This variable was added in MariaDB 5.6.1.

bulk_insert_buffer_size

Command-Line Format	`--bulk_insert_buffer_size=#`
Option-File Format	`bulk_insert_buffer_size`
Option Sets Variable	Yes, `bulk_insert_buffer_size`
Variable Name	`bulk_insert_buffer_size`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`8388608`
	Range	`0 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`8388608`
	Range	`0 .. 18446744073709547520`

MyISAM uses a special tree-like cache to make bulk inserts faster for INSERT ... SELECT, INSERT ... VALUES (...), (...), ..., and LOAD DATA INFILE when adding data to nonempty tables. This variable limits the size of the cache tree in bytes per thread. Setting it to 0 disables this optimization. The default value is 8MB.

character_set_client

Variable Name character_set_client
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type string

The character set for statements that arrive from the client. The session value of this variable is set using the character set requested by the client when the client connects to the server. (Many clients support a --default-character-set option to enable this character set to be specified explicitly. See also , "Connection Character Sets and Collations".) The global value of the variable is used to set the session value in cases when the client-requested value is unknown or not available, or the server is configured to ignore client requests:
- The client is from a version of MariaDB older than MySQL, and thus does not request a character set.
- The client requests a character set not known to the server. For example, a Japanese-enabled client requests sjis when connecting to a server not configured with sjis support.
- mysqld was started with the --skip-character-set-client-handshake option, which causes it to ignore client character set configuration. This reproduces MariaDB behavior and is useful should you wish to upgrade the server without upgrading all the clients.
ucs2, utf16, utf16le, and utf32 cannot be used as a client character set, which means that they also do not work for SET NAMES or SET CHARACTER SET.
character_set_connection

Variable Name character_set_connection
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type string

The character set used for literals that do not have a character set introducer and for number-to-string conversion.

character_set_database

Variable Name	`character_set_database`
Variable Scope	Global, Session
Dynamic Variable	Yes
Footnote	This option is dynamic, but only the server should set this information. You should not set the value of this variable manually.
	Permitted Values
	Type	`string`

The character set used by the default database. The server sets this variable whenever the default database changes. If there is no default database, the variable has the same value as character_set_server.

character_set_filesystem

Command-Line Format	`--character-set-filesystem=name`
Option-File Format	`character-set-filesystem`
Option Sets Variable	Yes, `character_set_filesystem`
Variable Name	`character_set_filesystem`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`string`

The file system character set. This variable is used to interpret string literals that refer to file names, such as in the LOAD DATA INFILE and SELECT ... INTO OUTFILE statements and the LOAD_FILE() function. Such file names are converted from character_set_client to character_set_filesystem before the file opening attempt occurs. The default value is binary, which means that no conversion occurs. For systems on which multi-byte file names are permitted, a different value may be more appropriate. For example, if the system represents file names using UTF-8, set character_set_filesystem to 'utf8'.

character_set_results

Variable Name character_set_results
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type string

The character set used for returning query results such as result sets or error messages to the client.

character_set_server

Command-Line Format	`--character-set-server`
Option-File Format	`character-set-server`
Option Sets Variable	Yes, `character_set_server`
Variable Name	`character_set_server`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`string`

The server's default character set.

character_set_system

Variable Name character_set_system
Variable Scope Global
Dynamic Variable No
Permitted Values
Type string

The character set used by the server for storing identifiers. The value is always utf8.

character_sets_dir

Command-Line Format	`--character-sets-dir=path`
Option-File Format	`character-sets-dir=path`
Option Sets Variable	Yes, `character_sets_dir`
Variable Name	`character-sets-dir`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`directory name`

The directory where character sets are installed.

collation_connection

Variable Name collation_connection
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type string

The collation of the connection character set.

collation_database

Variable Name	`collation_database`
Variable Scope	Global, Session
Dynamic Variable	Yes
Footnote	This option is dynamic, but only the server should set this information. You should not set the value of this variable manually.
	Permitted Values
	Type	`string`

The collation used by the default database. The server sets this variable whenever the default database changes. If there is no default database, the variable has the same value as collation_server.

collation_server

Command-Line Format	`--collation-server`
Option-File Format	`collation-server`
Option Sets Variable	Yes, `collation_server`
Variable Name	`collation_server`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`string`

The server's default collation.

completion_type

Command-Line Format	`--completion_type=#`
Option-File Format	`completion_type`
Option Sets Variable	Yes, `completion_type`
Variable Name	`completion_type`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`enumeration`
	Default	`NO_CHAIN`
	Valid Values	`NO_CHAIN` `CHAIN` `RELEASE` `0` `1` `2`

The transaction completion type. This variable can take the values shown in the following table. The variable can be assigned using either the name values or corresponding integer values.

Value	Description
`NO_CHAIN` (or 0)	`COMMIT` and `ROLLBACK` are unaffected. This is the default value.
`CHAIN` (or 1)	`COMMIT` and `ROLLBACK` are equivalent to `COMMIT AND CHAIN` and `ROLLBACK AND CHAIN`, respectively. (A new transaction starts immediately with the same isolation level as the just-terminated transaction.)
`RELEASE` (or 2)	`COMMIT` and `ROLLBACK` are equivalent to `COMMIT RELEASE` and `ROLLBACK RELEASE`, respectively. (The server disconnects after terminating the transaction.)

completion-type affects transactions that begin with START TRANSACTION or BEGIN and end with COMMIT or ROLLBACK. It does not apply to implicit commits resulting from execution of the statements listed in , "Statements That Cause an Implicit Commit". It also does not apply for XA COMMIT, XA ROLLBACK, or when autocommit=1.

concurrent_insert

Command-Line Format	`--concurrent_insert[=#]`
Option-File Format	`concurrent_insert`
Option Sets Variable	Yes, `concurrent_insert`
Variable Name	`concurrent_insert`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`enumeration`
	Default	`AUTO`
	Valid Values	`NEVER` `AUTO` `ALWAYS` `0` `1` `2`

If AUTO (the default), MariaDB permits INSERT and SELECT statements to run concurrently for MyISAM tables that have no free blocks in the middle of the data file. If you start mysqld with --skip-new, this variable is set to NEVER.

This variable can take the values shown in the following table. The variable can be assigned using either the name values or corresponding integer values.

Value	Description
`NEVER` (or 0)	Disables concurrent inserts
`AUTO` (or 1)	(Default) Enables concurrent insert for `MyISAM` tables that do not have holes
`ALWAYS` (or 2)	Enables concurrent inserts for all `MyISAM` tables, even those that have holes. For a table with a hole, new rows are inserted at the end of the table if it is in use by another thread. Otherwise, MariaDB acquires a normal write lock and inserts the row into the hole.

See also , "Concurrent Inserts".

connect_timeout

Command-Line Format	`--connect_timeout=#`
Option-File Format	`connect_timeout`
Option Sets Variable	Yes, `connect_timeout`
Variable Name	`connect_timeout`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`10`

The number of seconds that the mysqld server waits for a connect packet before responding with Bad handshake. The default value is 10 seconds.

Increasing the connect_timeout value might help if clients frequently encounter errors of the form Lost connection to MariaDB server at 'XXX', system error: errno.

datadir

Command-Line Format	`--datadir=path`
	`-h`
Option-File Format	`datadir`
Option Sets Variable	Yes, `datadir`
Variable Name	`datadir`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`file name`

The MariaDB data directory. This variable can be set with the --datadir option.

date_format
This variable is unused.
datetime_format
This variable is unused.

debug

Command-Line Format	`--debug[=debug_options]`
Option-File Format	`debug`
Variable Name	`debug`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`string`
	Default	`'d:t:o,/tmp/mysqld.trace'`

This variable indicates the current debugging settings. It is available only for servers built with debugging support. The initial value comes from the value of instances of the --debug option given at server startup. The global and session values may be set at runtime; the SUPER privilege is required, even for the session value.

Assigning a value that begins with + or - cause the value to added to or subtracted from the current value:

mysql> SET debug = 'T';
mysql> SELECT @@debug;
+---------+
| @@debug |
+---------+
| T |
+---------+
mysql> SET debug = '+P';
mysql> SELECT @@debug;
+---------+
| @@debug |
+---------+
| P:T |
+---------+
mysql> SET debug = '-P';
mysql> SELECT @@debug;
+---------+
| @@debug |
+---------+
| T |
+---------+

debug_sync

Variable Name debug_sync
Variable Scope Session
Dynamic Variable Yes
Permitted Values
Type string

This variable is the user interface to the Debug Sync facility. Use of Debug Sync requires that MariaDB be configured with the -DENABLE_DEBUG_SYNC=1 option (see , "MySQL Source-Configuration Options"). If Debug Sync is not compiled in, this system variable is not available.
The global variable value is read only and indicates whether the facility is enabled. By default, Debug Sync is disabled and the value of debug_sync is OFF. If the server is started with --debug-sync-timeout=N, where N is a timeout value greater than 0, Debug Sync is enabled and the value of debug_sync is ON - current signal followed by the signal name. Also, N becomes the default timeout for individual synchronization points.
The session value can be read by any user and will have the same value as the global variable. The session value can be set by users that have the SUPER privilege to control synchronization points.
For a description of the Debug Sync facility and how to use synchronization points, see MySQL Internals: Test Synchronization.

default_storage_engine

Command-Line Format	`--default-storage-engine=name`
Option-File Format	`default-storage-engine`
Option Sets Variable	Yes, `default_storage_engine`
Variable Name	`default_storage_engine`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`enumeration`
	Default	`InnoDB`

The default storage engine. As of MariaDB 5.6.3, this variable sets the storage engine for permanent tables only. To set the storage engine for TEMPORARY tables, set the default_tmp_storage_engine system variable.

default-storage-engine should be used in preference to storage_engine, which is deprecated.

If you disable the default storage engine at server startup, you must set the default engine for both permanent and TEMPORARY tables to a different engine or the server will not start.

default_tmp_storage_engine
The default storage engine for TEMPORARY tables (created with CREATE TEMPORARY TABLE). To set the storage engine for permanent tables, set the default_storage_engine system variable.
If you disable the default storage engine at server startup, you must set the default engine for both permanent and TEMPORARY tables to a different engine or the server will not start.
default_tmp_storage_engine was added in MariaDB 5.6.3.

default_week_format

Command-Line Format	`--default_week_format=#`
Option-File Format	`default_week_format`
Option Sets Variable	Yes, `default_week_format`
Variable Name	`default_week_format`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`0`
	Range	`0 .. 7`

The default mode value to use for the WEEK() function. See , "Date and Time Functions".

delay_key_write

Command-Line Format	`--delay-key-write[=name]`
Option-File Format	`delay-key-write`
Option Sets Variable	Yes, `delay_key_write`
Variable Name	`delay-key-write`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`enumeration`
	Default	`ON`
	Valid Values	`ON` `OFF` `ALL`

This option applies only to MyISAM tables. It can have one of the following values to affect handling of the DELAY_KEY_WRITE table option that can be used in CREATE TABLE statements.

Option	Description
`OFF`	`DELAY_KEY_WRITE` is ignored.
`ON`	MySQL honors any `DELAY_KEY_WRITE` option specified in `CREATE TABLE` statements. This is the default value.
`ALL`	All new opened tables are treated as if they were created with the `DELAY_KEY_WRITE` option enabled.

If DELAY_KEY_WRITE is enabled for a table, the key buffer is not flushed for the table on every index update, but only when the table is closed. This speeds up writes on keys a lot, but if you use this feature, you should add automatic checking of all MyISAM tables by starting the server with the --myisam-recover-options option (for example, --myisam-recover-options=BACKUP,FORCE). See , "Server Command Options", and , "MyISAM Startup Options".Warning

If you enable external locking with --external-locking, there is no protection against index corruption for tables that use delayed key writes.

delayed_insert_limit

Command-Line Format	`--delayed_insert_limit=#`
Option-File Format	`delayed_insert_limit`
Option Sets Variable	Yes, `delayed_insert_limit`
Variable Name	`delayed_insert_limit`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`100`
	Range	`1 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`100`
	Range	`1 .. 18446744073709547520`

After inserting delayed-insert-limit delayed rows into a nontransactional table, the INSERT DELAYED handler thread checks whether there are any SELECT statements pending. If so, it permits them to execute before continuing to insert delayed rows.

delayed_insert_timeout

Command-Line Format	`--delayed_insert_timeout=#`
Option-File Format	`delayed_insert_timeout`
Option Sets Variable	Yes, `delayed_insert_timeout`
Variable Name	`delayed_insert_timeout`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`300`

How many seconds an INSERT DELAYED handler thread should wait for INSERT statements before terminating.

delayed_queue_size

Command-Line Format	`--delayed_queue_size=#`
Option-File Format	`delayed_queue_size`
Option Sets Variable	Yes, `delayed_queue_size`
Variable Name	`delayed_queue_size`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`1000`
	Range	`1 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`1000`
	Range	`1 .. 18446744073709547520`

This is a per-table limit on the number of rows to queue when handling INSERT DELAYED statements for nontransactional tables. If the queue becomes full, any client that issues an INSERT DELAYED statement waits until there is room in the queue again.

div_precision_increment

Command-Line Format	`--div_precision_increment=#`
Option-File Format	`div_precision_increment`
Option Sets Variable	Yes, `div_precision_increment`
Variable Name	`div_precision_increment`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`4`
	Range	`0 .. 30`

This variable indicates the number of digits by which to increase the scale of the result of division operations performed with the / operator. The default value is 4. The minimum and maximum values are 0 and 30, respectively. The following example illustrates the effect of increasing the default value.

mysql> SELECT 1/7;
+--------+
| 1/7 |
+--------+
| 0.1429 |
+--------+
mysql> SET div_precision_increment = 12;
mysql> SELECT 1/7;
+----------------+
| 1/7 |
+----------------+
| 0.142857142857 |
+----------------+

engine_condition_pushdown

Version Removed	5.6.1
Command-Line Format	`--engine-condition-pushdown`
Option-File Format	`engine-condition-pushdown`
Option Sets Variable	Yes, `engine_condition_pushdown`
Variable Name	`engine_condition_pushdown`
Variable Scope	Global, Session
Dynamic Variable	Yes
Deprecated	5.5.3, by `optimizer_switch`
	Permitted Values
	Type	`boolean`
	Default	`ON`

This variable was removed in MariaDB 5.6.1. Use the engine_condition_pushdown flag of the optimizer_switch variable instead. See , "Controlling Switchable Optimizations".

end_markers_in_json

Version Introduced 5.6.5
Variable Name end_markers_in_json
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type boolean
Default OFF

Whether optimizer JSON output should add end markers.

eq_range_index_dive_limit

Version Introduced	5.6.5
Command-Line Format	`--eq_range_index_dive_limit=#`
Option-File Format	`eq_range_index_dive_limit`
Option Sets Variable	Yes, `eq_range_index_dive_limit`
Variable Name	`eq_range_index_dive_limit`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`10`
	Range	`0 .. 4294967295`

This variable indicates the number of equality ranges in an equality comparison condition when the optimizer should switch from using index dives to index statistics in estimating the number of qualifying rows. It applies to evaluation of expressions that have either of these equivalent forms, where the optimizer uses a non-unique index to look up col_name values:

col_name IN(val1, ..., valN)
col_name = val1 OR ... OR col_name = valN

In both cases, the expression contains N equality ranges. The optimizer can make row estimates using index dives or index statistics. If eq_range_index_dive_limit is greater than 0, the optimizer uses existing index statistics instead of index dives if there are eq_range_index_dive_limit or more equality ranges. Thus, to permit use of index dives for up to N equality ranges, set eq_range_index_dive_limit to N + 1. Set eq_range_index_dive_limit to 0 to disable use of index statistics and always use index dives regardless of N.

For more information, see , "Equality Range Optimization of Many-Valued Comparisons".

This variable was added in MariaDB 5.6.5. Before 5.6.5, the optimizer makes row estimates using index dives in all cases.

To update table index statistics for best estimates, use ANALYZE TABLE.

error_count
The number of errors that resulted from the last statement that generated messages. This variable is read only. See , "SHOW ERRORS Syntax".

event_scheduler

Command-Line Format	`--event-scheduler[=value]`
Option-File Format	`event-scheduler`
Option Sets Variable	Yes, `event_scheduler`
Variable Name	`event_scheduler`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`enumeration`
	Default	`OFF`
	Valid Values	`ON` `OFF` `DISABLED`

This variable indicates the status of the Event Scheduler; possible values are ON, OFF, and DISABLED, with the default being OFF. This variable and its effects on the Event Scheduler's operation are discussed in greater detail in the Overview section of the Events chapter.

expire_logs_days

Command-Line Format	`--expire_logs_days=#`
Option-File Format	`expire_logs_days`
Option Sets Variable	Yes, `expire_logs_days`
Variable Name	`expire_logs_days`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`0`
	Range	`0 .. 99`

The number of days for automatic binary log file removal. The default is 0, which means "no automatic removal." Possible removals happen at startup and when the binary log is flushed. Log flushing occurs as indicated in , "MySQL Server Logs".

To remove binary log files manually, use the PURGE BINARY LOGS statement. See , "PURGE BINARY LOGS Syntax".

external_user

Variable Name external_user
Variable Scope Session
Dynamic Variable No
Permitted Values
Type string

The external user name used during the authentication process, as set by the plugin used to authenticate the client. With native (built-in) MariaDB authentication, or if the plugin does not set the value, this variable is NULL. See , "Proxy Users".
flush

Command-Line Format --flush
Option-File Format flush
Variable Name flush
Variable Scope Global
Dynamic Variable Yes
Permitted Values
Type boolean
Default OFF

If ON, the server flushes (synchronizes) all changes to disk after each SQL statement. Normally, MariaDB does a write of all changes to disk only after each SQL statement and lets the operating system handle the synchronizing to disk. See "What to Do If MariaDB Keeps Crashing". This variable is set to ON if you start mysqld with the --flush option.

flush_time

Command-Line Format	`--flush_time=#`
Option-File Format	`flush_time`
Option Sets Variable	Yes, `flush_time`
Variable Name	`flush_time`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`0`
	Min Value	`0`
	Permitted Values
	Type (windows)	`numeric`
	Default	`1800`
	Min Value	`0`

If this is set to a nonzero value, all tables are closed every flush_time seconds to free up resources and synchronize unflushed data to disk. This option is best used only on Windows 9x or Me, or on systems with minimal resources.

foreign_key_checks
If set to 1 (the default), foreign key constraints for InnoDB tables are checked. If set to 0, they are ignored. Typically you leave this setting enabled during normal operation, to enforce referential integrity. Disabling foreign key checking can be useful for reloading InnoDB tables in an order different from that required by their parent/child relationships. See , "FOREIGN KEY Constraints".
Setting foreign_key_checks to 0 also affects data definition statements: DROP SCHEMA drops a schema even if it contains tables that have foreign keys that are referred to by tables outside the schema, and DROP TABLE drops tables that have foreign keys that are referred to by other tables.Note
Setting foreign_key_checks to 1 does not trigger a scan of the existing table data. Therefore, rows added to the table while foreign_key_checks = 0 will not be verified for consistency.

ft_boolean_syntax

Command-Line Format	`--ft_boolean_syntax=name`
Option-File Format	`ft_boolean_syntax`
Variable Name	`ft_boolean_syntax`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`string`
	Default	`+-><()~*:''&`

The list of operators supported by boolean full-text searches performed using IN BOOLEAN MODE. See , "Boolean Full-Text Searches".

The default variable value is '+ -><()~*:''&|'. The rules for changing the value are as follows:

Operator function is determined by position within the string.
The replacement value must be 14 characters.
Each character must be an ASCII nonalphanumeric character.
Either the first or second character must be a space.
No duplicates are permitted except the phrase quoting operators in positions 11 and 12. These two characters are not required to be the same, but they are the only two that may be.
Positions 10, 13, and 14 (which by default are set to ":", "&", and "|") are reserved for future extensions.

ft_max_word_len

Command-Line Format	`--ft_max_word_len=#`
Option-File Format	`ft_max_word_len`
Option Sets Variable	Yes, `ft_max_word_len`
Variable Name	`ft_max_word_len`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`numeric`
	Min Value	`10`

The maximum length of the word to be included in a MyISAM FULLTEXT index.Note

FULLTEXT indexes on MyISAM tables must be rebuilt after changing this variable. Use REPAIR TABLE tbl_name QUICK.

ft_min_word_len

Command-Line Format	`--ft_min_word_len=#`
Option-File Format	`ft_min_word_len`
Option Sets Variable	Yes, `ft_min_word_len`
Variable Name	`ft_min_word_len`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`numeric`
	Default	`4`
	Min Value	`1`

The minimum length of the word to be included in a MyISAM FULLTEXT index.Note

FULLTEXT indexes on MyISAM tables must be rebuilt after changing this variable. Use REPAIR TABLE tbl_name QUICK.

ft_query_expansion_limit

Command-Line Format	`--ft_query_expansion_limit=#`
Option-File Format	`ft_query_expansion_limit`
Option Sets Variable	Yes, `ft_query_expansion_limit`
Variable Name	`ft_query_expansion_limit`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`numeric`
	Default	`20`
	Range	`0 .. 1000`

The number of top matches to use for full-text searches performed using WITH QUERY EXPANSION.

ft_stopword_file

Command-Line Format	`--ft_stopword_file=file_name`
Option-File Format	`ft_stopword_file=file_name`
Option Sets Variable	Yes, `ft_stopword_file`
Variable Name	`ft_stopword_file`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`file name`

The file from which to read the list of stopwords for full-text searches on MyISAM tables. The server looks for the file in the data directory unless an absolute path name is given to specify a different directory. All the words from the file are used; comments are not honored. By default, a built-in list of stopwords is used (as defined in the storage/myisam/ft_static.c file). Setting this variable to the empty string ('') disables stopword filtering. See also , "Full-Text Stopwords".Note

FULLTEXT indexes on MyISAM tables must be rebuilt after changing this variable or the contents of the stopword file. Use REPAIR TABLE tbl_name QUICK.

general_log

Command-Line Format	`--general-log`
Option-File Format	`general-log`
Option Sets Variable	Yes, `general_log`
Variable Name	`general_log`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`OFF`

Whether the general query log is enabled. The value can be 0 (or OFF) to disable the log or 1 (or ON) to enable the log. The default value depends on whether the --general_log option is given. The destination for log output is controlled by the log_output system variable; if that value is NONE, no log entries are written even if the log is enabled.

general_log_file

Command-Line Format	`--general-log-file=file_name`
Option-File Format	`general_log_file`
Option Sets Variable	Yes, `general_log_file`
Variable Name	`general_log_file`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`file name`
	Default	`host_name.log`

The name of the general query log file. The default value is host_name.log, but the initial value can be changed with the --general_log_file option.

group_concat_max_len

Command-Line Format	`--group_concat_max_len=#`
Option-File Format	`group_concat_max_len`
Option Sets Variable	Yes, `group_concat_max_len`
Variable Name	`group_concat_max_len`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`1024`
	Range	`4 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`1024`
	Range	`4 .. 18446744073709547520`

The maximum permitted result length in bytes for the GROUP_CONCAT() function. The default is 1024.

have_compress
YES if the zlib compression library is available to the server, NO if not. If not, the COMPRESS() and UNCOMPRESS() functions cannot be used.
have_crypt
YES if the crypt() system call is available to the server, NO if not. If not, the ENCRYPT() function cannot be used.
have_csv
YES if mysqld supports CSV tables, NO if not.
This variable was removed in MariaDB 5.6.1. Use SHOW ENGINES instead.
have_dynamic_loading
YES if mysqld supports dynamic loading of plugins, NO if not.
have_geometry
YES if the server supports spatial data types, NO if not.
have_innodb
YES if mysqld supports InnoDB tables. DISABLED if --skip-innodb is used.
This variable was removed in MariaDB 5.6.1. Use SHOW ENGINES instead.
have_openssl
This variable is an alias for have_ssl.
have_partitioning
YES if mysqld supports partitioning.
This variable was removed in MariaDB 5.6.1. Use SHOW ENGINES instead.
have_profiling
YES if statement profiling is enabled, NO if not. See , "SHOW PROFILE Syntax".
have_query_cache
YES if mysqld supports the query cache, NO if not.
have_rtree_keys
YES if RTREE indexes are available, NO if not. (These are used for spatial indexes in MyISAM tables.)
have_ssl
YES if mysqld supports SSL connections, NO if not. DISABLED indicates that the server was compiled with SSL support, but but was not started with the appropriate --ssl-xxx options. See , "Using SSL Connections", for more information.
have_symlink
YES if symbolic link support is enabled, NO if not. This is required on Unix for support of the DATA DIRECTORY and INDEX DIRECTORY table options, and on Windows for support of data directory symlinks.

host_cache_size

Version Introduced	5.6.5
Command-Line Format	`--host_cache_size=#`
Option-File Format	`host_cache_size`
Option Sets Variable	Yes, `host_cache_size`
Variable Name	`host_cache_size`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`128`
	Range	`0 .. 65536`

The size of the internal host cache (see , "DNS Lookup Optimization and the Host Cache"). Setting the size to 0 disables the host cache. Changing the cache size at runtime implicitly causes a FLUSH HOSTS operation to clear the host cache and truncate the host_cache table.

Use of --skip-host-cache is similar to setting the host_cache_size system variable to 0, but host_cache_size is more flexible because it can also be used to resize, enable, or disable the host cache at runtime, not just at server startup. If you start the server with --skip-host-cache, the host cache cannot be re-enabled at runtime.

This variable was added in MariaDB 5.6.5.

hostname

Variable Name hostname
Variable Scope Global
Dynamic Variable No
Permitted Values
Type string

The server sets this variable to the server host name at startup.
identity
This variable is a synonym for the last_insert_id variable. It exists for compatibility with other database systems. You can read its value with SELECT @@identity, and set it using SET identity.
ignore_db_dirs

Version Introduced 5.6.3
Variable Name ignore_db_dirs
Variable Scope Global
Dynamic Variable No
Permitted Values
Type string

A comma-separated list of names that are not considered as database directories in the data directory. The value is set from any instances of --ignore-db-dir given at server startup.
This variable was added in MariaDB 5.6.3.

init_connect

Command-Line Format	`--init-connect=name`
Option-File Format	`init_connect`
Option Sets Variable	Yes, `init_connect`
Variable Name	`init_connect`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`string`

A string to be executed by the server for each client that connects. The string consists of one or more SQL statements, separated by semicolon characters. For example, each client session begins by default with autocommit mode enabled. For older servers (before MariaDB 5.5.8), there is no global autocommit system variable to specify that autocommit should be disabled by default, but as a workaround init_connect can be used to achieve the same effect:

SET GLOBAL init_connect='SET autocommit=0';

The init_connect variable can also be set on the command line or in an option file. To set the variable as just shown using an option file, include these lines:

[mysqld]
init_connect='SET autocommit=0'

The content of init-connect is not executed for users that have the SUPER privilege. This is done so that an erroneous value for init_connect does not prevent all clients from connecting. For example, the value might contain a statement that has a syntax error, thus causing client connections to fail. Not executing init_connect for users that have the SUPER privilege enables them to open a connection and fix the init_connect value.

init_file

Command-Line Format	`--init-file=file_name`
Option-File Format	`init-file=file_name`
Option Sets Variable	Yes, `init_file`
Variable Name	`init_file`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`file name`

The name of the file specified with the --init-file option when you start the server. This should be a file containing SQL statements that you want the server to execute when it starts. Each statement must be on a single line and should not include comments. No statement terminator such as ;, \g, or \G should be given at the end of each statement.

Note that the --init-file option is unavailable if MariaDB was configured with the DISABLE_GRANT_OPTIONS compiler flag. See , "MySQL Source-Configuration Options".

innodb_xxx
InnoDB system variables are listed in , "InnoDB Startup Options and System Variables".
insert_id
The value to be used by the following INSERT or ALTER TABLE statement when inserting an AUTO_INCREMENT value. This is mainly used with the binary log.

interactive_timeout

Command-Line Format	`--interactive_timeout=#`
Option-File Format	`interactive_timeout`
Option Sets Variable	Yes, `interactive_timeout`
Variable Name	`interactive_timeout`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`28800`
	Min Value	`1`

The number of seconds the server waits for activity on an interactive connection before closing it. An interactive client is defined as a client that uses the CLIENT_INTERACTIVE option to mysql_real_connect(). See also wait_timeout.

join_buffer_size

Command-Line Format	`--join_buffer_size=#`
Option-File Format	`join_buffer_size`
Option Sets Variable	Yes, `join_buffer_size`
Variable Name	`join_buffer_size`
Variable Scope	Global, Session
Dynamic Variable	Yes

The minimum size of the buffer that is used for plain index scans, range index scans, and joins that do not use indexes and thus perform full table scans. Normally, the best way to get fast joins is to add indexes. Increase the value of join_buffer_size to get a faster full join when adding indexes is not possible. One join buffer is allocated for each full join between two tables. For a complex join between several tables for which indexes are not used, multiple join buffers might be necessary. There is no gain from setting the buffer larger than required to hold each matching row, and all joins allocate at least the minimum size, so use caution in setting this variable to a large value globally. It is better to keep the global setting small and change to a larger setting only in sessions that are doing large joins. Memory allocation time can cause substantial performance drops if the global size is larger than needed by most queries that use it.

The maximum permissible setting for join_buffer_size is 4GB. Values larger than 4GB are permitted for 64-bit platforms (except 64-bit Windows, for which large values are truncated to 4GB with a warning).

keep_files_on_create

Command-Line Format	`--keep_files_on_create=#`
Option-File Format	`keep_files_on_create`
Option Sets Variable	Yes, `keep_files_on_create`
Variable Name	`keep_files_on_create`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`OFF`

If a MyISAM table is created with no DATA DIRECTORY option, the .MYD file is created in the database directory. By default, if MyISAM finds an existing .MYD file in this case, it overwrites it. The same applies to .MYI files for tables created with no INDEX DIRECTORY option. To suppress this behavior, set the keep_files_on_create variable to ON (1), in which case MyISAM will not overwrite existing files and returns an error instead. The default value is OFF (0).

If a MyISAM table is created with a DATA DIRECTORY or INDEX DIRECTORY option and an existing .MYD or .MYI file is found, MyISAM always returns an error. It will not overwrite a file in the specified directory.

key_buffer_size

Command-Line Format	`--key_buffer_size=#`
Option-File Format	`key_buffer_size`
Option Sets Variable	Yes, `key_buffer_size`
Variable Name	`key_buffer_size`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`8388608`
	Range	`8 .. 4294967295`

Index blocks for MyISAM tables are buffered and are shared by all threads. key_buffer_size is the size of the buffer used for index blocks. The key buffer is also known as the key cache.

The maximum permissible setting for key_buffer_size is 4GB on 32-bit platforms. Values larger than 4GB are permitted for 64-bit platforms. The effective maximum size might be less, depending on your available physical RAM and per-process RAM limits imposed by your operating system or hardware platform. The value of this variable indicates the amount of memory requested. Internally, the server allocates as much memory as possible up to this amount, but the actual allocation might be less.

You can increase the value to get better index handling for all reads and multiple writes; on a system whose primary function is to run MariaDB using the MyISAM storage engine, 25% of the machine's total memory is an acceptable value for this variable. However, you should be aware that, if you make the value too large (for example, more than 50% of the machine's total memory), your system might start to page and become extremely slow. This is because MariaDB relies on the operating system to perform file system caching for data reads, so you must leave some room for the file system cache. You should also consider the memory requirements of any other storage engines that you may be using in addition to MyISAM.

For even more speed when writing many rows at the same time, use LOCK TABLES. See , "Speed of INSERT Statements".

You can check the performance of the key buffer by issuing a SHOW STATUS statement and examining the Key_read_requests, Key_reads, Key_write_requests, and Key_writes status variables. (See , "SHOW Syntax".) The Key_reads/Key_read_requests ratio should normally be less than 0.01. The Key_writes/Key_write_requests ratio is usually near 1 if you are using mostly updates and deletes, but might be much smaller if you tend to do updates that affect many rows at the same time or if you are using the DELAY_KEY_WRITE table option.

The fraction of the key buffer in use can be determined using key_buffer_size in conjunction with the Key_blocks_unused status variable and the buffer block size, which is available from the key_cache_block_size system variable:

1 - ((Key_blocks_unused * key_cache_block_size) / key_buffer_size)

This value is an approximation because some space in the key buffer is allocated internally for administrative structures. Factors that influence the amount of overhead for these structures include block size and pointer size. As block size increases, the percentage of the key buffer lost to overhead tends to decrease. Larger blocks results in a smaller number of read operations (because more keys are obtained per read), but conversely an increase in reads of keys that are not examined (if not all keys in a block are relevant to a query).

It is possible to create multiple MyISAM key caches. The size limit of 4GB applies to each cache individually, not as a group. See , "The MyISAM Key Cache".

key_cache_age_threshold

Command-Line Format	`--key_cache_age_threshold=#`
Option-File Format	`key_cache_age_threshold`
Option Sets Variable	Yes, `key_cache_age_threshold`
Variable Name	`key_cache_age_threshold`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`300`
	Range	`4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`300`
	Range	`18446744073709547520`

This value controls the demotion of buffers from the hot sublist of a key cache to the warm sublist. Lower values cause demotion to happen more quickly. The minimum value is 100. The default value is 300. See , "The MyISAM Key Cache".

key_cache_block_size

Command-Line Format	`--key_cache_block_size=#`
Option-File Format	`key_cache_block_size`
Option Sets Variable	Yes, `key_cache_block_size`
Variable Name	`key_cache_block_size`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`1024`
	Range	`16384`

The size in bytes of blocks in the key cache. The default value is 1024. See , "The MyISAM Key Cache".

key_cache_division_limit

Command-Line Format	`--key_cache_division_limit=#`
Option-File Format	`key_cache_division_limit`
Option Sets Variable	Yes, `key_cache_division_limit`
Variable Name	`key_cache_division_limit`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`100`
	Range	`1 .. 100`

The division point between the hot and warm sublists of the key cache buffer list. The value is the percentage of the buffer list to use for the warm sublist. Permissible values range from 1 to 100. The default value is 100. See , "The MyISAM Key Cache".

large_files_support

Variable Name large_files_support
Variable Scope Global
Dynamic Variable No

Whether mysqld was compiled with options for large file support.

large_pages

Command-Line Format	`--large-pages`
Option-File Format	`large-pages`
Option Sets Variable	Yes, `large_pages`
Variable Name	`large_pages`
Variable Scope	Global
Dynamic Variable	No
Platform Specific	linux
	Permitted Values
	Type (linux)	`boolean`
	Default	`FALSE`

Whether large page support is enabled (via the --large-pages option). See , "Enabling Large Page Support".

large_page_size

Variable Name large_page_size
Variable Scope Global
Dynamic Variable No
Permitted Values
Type (linux) numeric
Default 0

If large page support is enabled, this shows the size of memory pages. Currently, large memory pages are supported only on Linux; on other platforms, the value of this variable is always 0. See , "Enabling Large Page Support".
last_insert_id
The value to be returned from LAST-INSERT-ID(). This is stored in the binary log when you use LAST_INSERT_ID() in a statement that updates a table. Setting this variable does not update the value returned by the mysql_insert_id() C API function.

lc_messages

Command-Line Format	`--lc-messages=name`
Option-File Format	`lc-messages`
Option Sets Variable	Yes, `lc_messages`
Variable Name	`lc-messages`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`string`

The locale to use for error messages. The server converts the value to a language name and combines it with the value of the lc_messages_dir to produce the location for the error message file. See , "Setting the Error Message Language".

lc_messages_dir

Command-Line Format	`--lc-messages-dir=path`
Option-File Format	`lc-messages-dir`
Option Sets Variable	Yes, `lc_messages_dir`
Variable Name	`lc-messages-dir`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`directory name`

The directory where error messages are located. The value is used together with the value of lc_messages to produce the location for the error message file. See , "Setting the Error Message Language".

lc_time_names

Variable Name lc_time_names
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type string

This variable specifies the locale that controls the language used to display day and month names and abbreviations. This variable affects the output from the DATE_FORMAT(), DAYNAME() and MONTHNAME() functions. Locale names are POSIX-style values such as 'ja_JP' or 'pt_BR'. The default value is 'en_US' regardless of your system's locale setting. For further information, see , "MySQL Server Locale Support".
license

Variable Name license
Variable Scope Global
Dynamic Variable No
Permitted Values
Type string
Default GPL

The type of license the server has.
local_infile

Variable Name local_infile
Variable Scope Global
Dynamic Variable Yes
Permitted Values
Type boolean

Whether LOCAL is supported for LOAD DATA INFILE statements. See , "Security Issues with LOAD DATA LOCAL".

lock_wait_timeout

Command-Line Format	`--lock_wait_timeout=#`
Option-File Format	`lock_wait_timeout`
Option Sets Variable	Yes, `lock_wait_timeout`
Variable Name	`lock_wait_timeout`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`31536000`
	Range	`1 .. 31536000`

This variable specifies the timeout in seconds for attempts to acquire metadata locks. The permissible values range from 1 to 31536000 (1 year). The default is 31536000.

This timeout applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures, and stored functions, as well as LOCK TABLES, FLUSH TABLES WITH READ LOCK, and HANDLER statements.

The timeout value applies separately for each metadata lock attempt. A given statement can require more than one lock, so it is possible for the statement to block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported.

lock_wait_timeout does not apply to delayed inserts, which always execute with a timeout of 1 year. This is done to avoid unnecessary timeouts because a session that issues a delayed insert receives no notification of delayed insert timeouts.

locked_in_memory

Variable Name locked_in_memory
Variable Scope Global
Dynamic Variable No

Whether mysqld was locked in memory with --memlock.
log
This variable removed in MariaDB 5.6.1. Use general_log instead.
log_bin

Variable Name log_bin
Variable Scope Global
Dynamic Variable No

Whether the binary log is enabled. If the --log-bin option is used, then the value of this variable is ON; otherwise it is OFF. This variable reports only on the status of binary logging (enabled or disabled); it does not actually report the value to which --log-bin is set.
See , "The Binary Log".

log_bin_trust_function_creators

Command-Line Format	`--log-bin-trust-function-creators`
Option-File Format	`log-bin-trust-function-creators`
Option Sets Variable	Yes, `log_bin_trust_function_creators`
Variable Name	`log_bin_trust_function_creators`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`FALSE`

This variable applies when binary logging is enabled. It controls whether stored function creators can be trusted not to create stored functions that will cause unsafe events to be written to the binary log. If set to 0 (the default), users are not permitted to create or alter stored functions unless they have the SUPER privilege in addition to the CREATE ROUTINE or ALTER ROUTINE privilege. A setting of 0 also enforces the restriction that a function must be declared with the DETERMINISTIC characteristic, or with the READS SQL DATA or NO SQL characteristic. If the variable is set to 1, MariaDB does not enforce these restrictions on stored function creation. This variable also applies to trigger creation. See , "Binary Logging of Stored Programs".

log_error

Command-Line Format	`--log-error[=name]`
Option-File Format	`log-error`
Option Sets Variable	Yes, `log_error`
Variable Name	`log_error`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`file name`

The location of the error log.

log_output

Command-Line Format	`--log-output[=name]`
Option-File Format	`log-output`
Option Sets Variable	Yes, `log_output`
Variable Name	`log_output`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`set`
	Default	`FILE`
	Valid Values	`TABLE` `FILE` `NONE`

The destination for general query log and slow query log output. The value can be a comma-separated list of one or more of the words TABLE (log to tables), FILE (log to files), or NONE (do not log to tables or files). The default value is TABLE. NONE, if present, takes precedence over any other specifiers. If the value is NONE log entries are not written even if the logs are enabled. If the logs are not enabled, no logging occurs even if the value of log_output is not NONE. For more information, see , "Selecting General Query and Slow Query Log Output Destinations".

log_queries_not_using_indexes

Command-Line Format	`--log-queries-not-using-indexes`
Option-File Format	`log-queries-not-using-indexes`
Option Sets Variable	Yes, `log_queries_not_using_indexes`
Variable Name	`log_queries_not_using_indexes`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`OFF`

Whether queries that do not use indexes are logged to the slow query log. See , "The Slow Query Log".

log_slave_updates
Whether updates received by a slave server from a master server should be logged to the slave's own binary log. Binary logging must be enabled on the slave for this variable to have any effect. See , "Replication and Binary Logging Options and Variables".
log_slow_admin_statements

Command-Line Format --log-slow-admin-statements
Option-File Format log-slow-admin-statements
Permitted Values
Type boolean
Default FALSE

When the slow query log is enabled, whether to log slow administrative statements such as OPTIMIZE TABLE, ANALYZE TABLE, and ALTER TABLE to the slow query log.
log_slow_slave_statements

Command-Line Format --log-slow-slave-statements
Option-File Format log-slow-slave-statements
Permitted Values
Type boolean
Default off

When the slow query log is enabled, whether to log queries that have taken more than long_query_time seconds to execute on the slave.

log_slow_queries

Version Removed	5.6.1
Command-Line Format	`--log-slow-queries[=name]`
Option-File Format	`log-slow-queries`
Option Sets Variable	Yes, `log_slow_queries`
Variable Name	`log_slow_queries`
Variable Scope	Global
Dynamic Variable	Yes
Deprecated	5.1.29, by `slow-query-log`
	Permitted Values
	Type	`boolean`

This variable was removed in MariaDB 5.6.1. Use slow_query_log instead.

log_throttle_queries_not_using_indexes

Version Introduced 5.6.5
Variable Name log_throttle_queries_not_using_indexes
Variable Scope Global
Dynamic Variable Yes
Permitted Values
Type numeric
Default 0

If log-queries-not-using-indexes is enabled, the log_throttle_queries_not_using_indexes variable limits the number of such queries per minute that can be written to the slow query log. A value of 0 (the default) means "no limit". For more information, see , "The Slow Query Log".
This variable was added in MariaDB 5.6.5.

log_warnings

Command-Line Format	`--log-warnings[=#]`
	`-W [#]`
Option-File Format	`log-warnings`
Option Sets Variable	Yes, `log_warnings`
Variable Name	`log_warnings`
Variable Scope	Global
Dynamic Variable	Yes
Disabled by	`skip-log-warnings`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`1`
	Range	`0 .. 18446744073709547520`

Whether to produce additional warning messages to the error log. It is enabled (1) by default and can be disabled by setting it to 0. Aborted connections and access-denied errors for new connection attempts are logged if the value is greater than 1. The server logs messages about statements that are unsafe for statement-based logging only if the value is greater than 0.

long_query_time

Command-Line Format	`--long_query_time=#`
Option-File Format	`long_query_time`
Option Sets Variable	Yes, `long_query_time`
Variable Name	`long_query_time`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`10`
	Min Value	`0`

If a query takes longer than this many seconds, the server increments the Slow_queries status variable. If the slow query log is enabled, the query is logged to the slow query log file. This value is measured in real time, not CPU time, so a query that is under the threshold on a lightly loaded system might be above the threshold on a heavily loaded one. The minimum and default values of long_query_time are 0 and 10, respectively. The value can be specified to a resolution of microseconds. For logging to a file, times are written including the microseconds part. For logging to tables, only integer times are written; the microseconds part is ignored. See , "The Slow Query Log".

low_priority_updates

Command-Line Format	`--low-priority-updates`
Option-File Format	`low-priority-updates`
Option Sets Variable	Yes, `low_priority_updates`
Variable Name	`low_priority_updates`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`FALSE`

If set to 1, all INSERT, UPDATE, DELETE, and LOCK TABLE WRITE statements wait until there is no pending SELECT or LOCK TABLE READ on the affected table. This affects only storage engines that use only table-level locking (such as MyISAM, MEMORY, and MERGE).

lower_case_file_system

Command-Line Format	`--lower_case_file_system[=#]`
Option-File Format	`lower_case_file_system`
Option Sets Variable	Yes, `lower_case_file_system`
Variable Name	`lower_case_file_system`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`boolean`

This variable describes the case sensitivity of file names on the file system where the data directory is located. OFF means file names are case sensitive, ON means they are not case sensitive. This variable is read only because it reflects a file system attribute and setting it would have no effect on the file system.

lower_case_table_names

Command-Line Format	`--lower_case_table_names[=#]`
Option-File Format	`lower_case_table_names`
Option Sets Variable	Yes, `lower_case_table_names`
Variable Name	`lower_case_table_names`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`numeric`
	Default	`0`
	Range	`0 .. 2`

If set to 0, table names are stored as specified and comparisons are case sensitive. If set to 1, table names are stored in lowercase on disk and comparisons are not case sensitive. If set to 2, table names are stored as given but compared in lowercase. This option also applies to database names and table aliases. For additional information, see , "Identifier Case Sensitivity".

You should not set this variable to 0 if you are running MariaDB on a system that has case-insensitive file names (such as Windows or Mac OS X). If you set this variable to 0 on such a system and access MyISAM tablenames using different lettercases, index corruption may result. On Windows the default value is 1. On Mac OS X, the default value is 2.

If you are using InnoDB tables, you should set this variable to 1 on all platforms to force names to be converted to lowercase.

The setting of this variable in MariaDB 5.6 effects the behavior of replication filtering options with regard to case sensitivity. This is a change from previous versions of MySQL. (Bug #51639) See , "How Servers Evaluate Replication Filtering Rules", for more information.

In previous versions of MySQL, using different settings for lower_case_table_names on replication masters and slaves could cause replication to fail when the slave used a case-sensitive file system. This issue is resolved in MariaDB 5.6.1. For more information, see , "Replication and Variables".

max_allowed_packet

Command-Line Format	`--max_allowed_packet=#`
Option-File Format	`max_allowed_packet`
Option Sets Variable	Yes, `max_allowed_packet`
Variable Name	`max_allowed_packet`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`1048576`
	Range	`1073741824`

The maximum size of one packet or any generated/intermediate string, or any parameter sent by the mysql_stmt_send_long_data() C API function.

The packet message buffer is initialized to net_buffer_length bytes, but can grow up to max_allowed_packet bytes when needed. This value by default is small, to catch large (possibly incorrect) packets.

You must increase this value if you are using large BLOB columns or long strings. It should be as big as the largest BLOB you want to use. The protocol limit for max_allowed_packet is 1GB. The value should be a multiple of 1024; nonmultiples are rounded down to the nearest multiple.

When you change the message buffer size by changing the value of the max_allowed_packet variable, you should also change the buffer size on the client side if your client program permits it. On the client side, max-allowed-packet has a default of 1GB. Some programs such as mysql and mysqldump enable you to change the client-side value by setting max_allowed_packet on the command line or in an option file.

The session value of this variable is read only.

max_connect_errors

Command-Line Format	`--max_connect_errors=#`
Option-File Format	`max_connect_errors`
Option Sets Variable	Yes, `max_connect_errors`
Variable Name	`max_connect_errors`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`10`
	Range	`1 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`10`
	Range	`1 .. 18446744073709547520`

If more than this many successive connection requests from a host are interrupted without a successful connection, the server blocks that host from further connections. You can unblock blocked hosts by flushing the host cache. To do so, issue a FLUSH HOSTS statement or execute a mysqladmin flush-hosts command. If a connection is established successfully within fewer than max_connect_errors attempts after a previous connection was interrupted, the error count for the host is cleared to zero. However, once a host is blocked, flushing the host cache is the only way to unblock it.

max_connections

Command-Line Format	`--max_connections=#`
Option-File Format	`max_connections`
Option Sets Variable	Yes, `max_connections`
Variable Name	`max_connections`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`151`
	Range	`1 .. 100000`

The maximum permitted number of simultaneous client connections. By default, this is 151. See "Too many connections", for more information.

Increasing this value increases the number of file descriptors that mysqld requires. See , "How MariaDB Opens and Closes Tables", for comments on file descriptor limits.

Connections refused because the max_connections limit is reached increment the Connection_errors_max_connections status variable.

max_delayed_threads

Command-Line Format	`--max_delayed_threads=#`
Option-File Format	`max_delayed_threads`
Option Sets Variable	Yes, `max_delayed_threads`
Variable Name	`max_delayed_threads`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`20`
	Range	`0 .. 16384`

Do not start more than this number of threads to handle INSERT DELAYED statements for nontransactional tables. If you try to insert data into a new table after all INSERT DELAYED threads are in use, the row is inserted as if the DELAYED attribute was not specified. If you set this to 0, MariaDB never creates a thread to handle DELAYED rows; in effect, this disables DELAYED entirely.

For the SESSION value of this variable, the only valid values are 0 or the GLOBAL value.

max_error_count

Command-Line Format	`--max_error_count=#`
Option-File Format	`max_error_count`
Option Sets Variable	Yes, `max_error_count`
Variable Name	`max_error_count`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`64`
	Range	`0 .. 65535`

The maximum number of error, warning, and note messages to be stored for display by the SHOW ERRORS and SHOW WARNINGS statements. This is the same as the number of condition areas in the diagnostics area, and thus the number of conditions that can be inspected by GET DIAGNOSTICS.

max_heap_table_size

Command-Line Format	`--max_heap_table_size=#`
Option-File Format	`max_heap_table_size`
Option Sets Variable	Yes, `max_heap_table_size`
Variable Name	`max_heap_table_size`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`16777216`
	Range	`4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`16777216`
	Range	`1844674407370954752`

This variable sets the maximum size to which user-created MEMORY tables are permitted to grow. The value of the variable is used to calculate MEMORY table MAX_ROWS values. Setting this variable has no effect on any existing MEMORY table, unless the table is re-created with a statement such as CREATE TABLE or altered with ALTER TABLE or TRUNCATE TABLE. A server restart also sets the maximum size of existing MEMORY tables to the global max_heap_table_size value.

This variable is also used in conjunction with tmp_table_size to limit the size of internal in-memory tables. See , "How MariaDB Uses Internal Temporary Tables".

max_heap_table_size is not replicated. See , "Replication and MEMORY Tables", and , "Replication and Variables", for more information.

max_insert_delayed_threads

Variable Name max_insert_delayed_threads
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type numeric

This variable is a synonym for max_delayed_threads.

max_join_size

Command-Line Format	`--max_join_size=#`
Option-File Format	`max_join_size`
Option Sets Variable	Yes, `max_join_size`
Variable Name	`max_join_size`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`18446744073709551615`
	Range	`1 .. 18446744073709551615`

Do not permit SELECT statements that probably need to examine more than max_join_size rows (for single-table statements) or row combinations (for multiple-table statements) or that are likely to do more than max_join_size disk seeks. By setting this value, you can catch SELECT statements where keys are not used properly and that would probably take a long time. Set it if your users tend to perform joins that lack a WHERE clause, that take a long time, or that return millions of rows.

Setting this variable to a value other than DEFAULT resets the value of sql_big_selects to 0. If you set the sql-big-selects value again, the max_join_size variable is ignored.

If a query result is in the query cache, no result size check is performed, because the result has previously been computed and it does not burden the server to send it to the client.

max_length_for_sort_data

Command-Line Format	`--max_length_for_sort_data=#`
Option-File Format	`max_length_for_sort_data`
Option Sets Variable	Yes, `max_length_for_sort_data`
Variable Name	`max_length_for_sort_data`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`1024`
	Range	`4 .. 8388608`

The cutoff on the size of index values that determines which filesort algorithm to use. See , "ORDER BY Optimization".

max_prepared_stmt_count

Command-Line Format	`--max_prepared_stmt_count=#`
Option-File Format	`max_prepared_stmt_count`
Option Sets Variable	Yes, `max_prepared_stmt_count`
Variable Name	`max_prepared_stmt_count`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`16382`
	Range	`0 .. 1048576`

This variable limits the total number of prepared statements in the server. It can be used in environments where there is the potential for denial-of-service attacks based on running the server out of memory by preparing huge numbers of statements. If the value is set lower than the current number of prepared statements, existing statements are not affected and can be used, but no new statements can be prepared until the current number drops below the limit. The default value is 16,382. The permissible range of values is from 0 to 1 million. Setting the value to 0 disables prepared statements.

max_relay_log_size

Command-Line Format	`--max_relay_log_size=#`
Option-File Format	`max_relay_log_size`
Option Sets Variable	Yes, `max_relay_log_size`
Variable Name	`max_relay_log_size`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`0`
	Range	`0 .. 1073741824`

If a write by a replication slave to its relay log causes the current log file size to exceed the value of this variable, the slave rotates the relay logs (closes the current file and opens the next one). If max_relay_log_size is 0, the server uses max_binlog_size for both the binary log and the relay log. If max_relay_log_size is greater than 0, it constrains the size of the relay log, which enables you to have different sizes for the two logs. You must set max_relay_log_size to between 4096 bytes and 1GB (inclusive), or to 0. The default value is 0. See , "Replication Implementation Details".

max_seeks_for_key

Command-Line Format	`--max_seeks_for_key=#`
Option-File Format	`max_seeks_for_key`
Option Sets Variable	Yes, `max_seeks_for_key`
Variable Name	`max_seeks_for_key`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`4294967295`
	Range	`1 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`18446744073709547520`
	Range	`1 .. 18446744073709547520`

Limit the assumed maximum number of seeks when looking up rows based on a key. The MariaDB optimizer assumes that no more than this number of key seeks are required when searching for matching rows in a table by scanning an index, regardless of the actual cardinality of the index (see , "SHOW INDEX Syntax"). By setting this to a low value (say, 100), you can force MariaDB to prefer indexes instead of table scans.

max_sort_length

Command-Line Format	`--max_sort_length=#`
Option-File Format	`max_sort_length`
Option Sets Variable	Yes, `max_sort_length`
Variable Name	`max_sort_length`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`1024`
	Range	`4 .. 8388608`

The number of bytes to use when sorting BLOB or TEXT values. Only the first max_sort_length bytes of each value are used; the rest are ignored.

max_sp_recursion_depth

Command-Line Format	`--max_sp_recursion_depth[=#]`
Option-File Format	`max_sp_recursion_depth`
Option Sets Variable	Yes, `max_sp_recursion_depth`
Variable Name	`max_sp_recursion_depth`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`0`
	Max Value	`255`

The number of times that any given stored procedure may be called recursively. The default value for this option is 0, which completely disables recursion in stored procedures. The maximum value is 255.

Stored procedure recursion increases the demand on thread stack space. If you increase the value of max_sp_recursion_depth, it may be necessary to increase thread stack size by increasing the value of thread_stack at server startup.

max_tmp_tables

Command-Line Format	`--max_tmp_tables=#`
Option-File Format	`max_tmp_tables`
Option Sets Variable	Yes, `max_tmp_tables`
Variable Name	`max_tmp_tables`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`32`
	Range	`1 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`32`
	Range	`1 .. 18446744073709547520`

The maximum number of temporary tables a client can keep open at the same time. (This variable does not yet do anything.)

max_user_connections

Command-Line Format	`--max_user_connections=#`
Option-File Format	`max_user_connections`
Option Sets Variable	Yes, `max_user_connections`
Variable Name	`max_user_connections`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`0`
	Range	`0 .. 4294967295`

The maximum number of simultaneous connections permitted to any given MariaDB user account. A value of 0 (the default) means "no limit."

This variable has a global value that can be set at server startup or runtime. It also has a read-only session value that indicates the effective simultaneous-connection limit that applies to the account associated with the current session. The session value is initialized as follows:

If the user account has a nonzero MAX_USER_CONNECTIONS resource limit, the session max_user_connections value is set to that limit.
Otherwise, the session max_user_connections value is set to the global value.

Account resource limits are specified using the GRANT statement. See , "Setting Account Resource Limits", and , "GRANT Syntax".

max_write_lock_count

Command-Line Format	`--max_write_lock_count=#`
Option-File Format	`max_write_lock_count`
Option Sets Variable	Yes, `max_write_lock_count`
Variable Name	`max_write_lock_count`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`4294967295`
	Range	`1 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`18446744073709547520`
	Range	`1 .. 18446744073709547520`

After this many write locks, permit some pending read lock requests to be processed in between.

metadata_locks_cache_size

Version Introduced 5.6.4
Variable Name metadata_locks_cache_size
Variable Scope Global
Dynamic Variable No
Permitted Values
Type numeric
Default 1024
Range 1 .. 1048576

The size of the metadata locks cache. The server uses this cache to avoid creation and destruction of synchronization objects. This is particularly helpful on systems where such operations are expensive, such as Windows XP. This variable was added in MariaDB 5.6.4.

min_examined_row_limit

Command-Line Format	`--min-examined-row-limit=#`
Option-File Format	`min-examined-row-limit`
Variable Name	`min_examined_row_limit`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`0`
	Range	`0 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`0`
	Range	`0 .. 18446744073709547520`

Queries that examine fewer than this number of rows are not logged to the slow query log.

myisam_data_pointer_size

Command-Line Format	`--myisam_data_pointer_size=#`
Option-File Format	`myisam_data_pointer_size`
Option Sets Variable	Yes, `myisam_data_pointer_size`
Variable Name	`myisam_data_pointer_size`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`6`
	Range	`2 .. 7`

The default pointer size in bytes, to be used by CREATE TABLE for MyISAM tables when no MAX_ROWS option is specified. This variable cannot be less than 2 or larger than 7. The default value is 6. See "The table is full".

myisam_max_sort_file_size

Command-Line Format	`--myisam_max_sort_file_size=#`
Option-File Format	`myisam_max_sort_file_size`
Option Sets Variable	Yes, `myisam_max_sort_file_size`
Variable Name	`myisam_max_sort_file_size`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`2147483648`

The maximum size of the temporary file that MariaDB is permitted to use while re-creating a MyISAM index (during REPAIR TABLE, ALTER TABLE, or LOAD DATA INFILE). If the file size would be larger than this value, the index is created using the key cache instead, which is slower. The value is given in bytes.

The default value is 2GB. If MyISAM index files exceed this size and disk space is available, increasing the value may help performance. The space must be available in the file system containing the directory where the original index file is located.

myisam_mmap_size

Command-Line Format	`--myisam_mmap_size=#`
Option-File Format	`myisam_mmap_size`
Option Sets Variable	Yes, `myisam_mmap_size`
Variable Name	`myisam_mmap_size`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`4294967295`
	Range	`7 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`18446744073709547520`
	Range	`7 .. 18446744073709547520`

The maximum amount of memory to use for memory mapping compressed MyISAM files. If many compressed MyISAM tables are used, the value can be decreased to reduce the likelihood of memory-swapping problems.

myisam_recover_options

Variable Name myisam_recover_options
Variable Scope Global
Dynamic Variable No

The value of the --myisam-recover-options option. See , "Server Command Options".

myisam_repair_threads

Command-Line Format	`--myisam_repair_threads=#`
Option-File Format	`myisam_repair_threads`
Option Sets Variable	Yes, `myisam_repair_threads`
Variable Name	`myisam_repair_threads`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`1`
	Range	`1 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`1`
	Range	`1 .. 18446744073709547520`

If this value is greater than 1, MyISAM table indexes are created in parallel (each index in its own thread) during the Repair by sorting process. The default value is 1.Note

Multi-threaded repair is still beta-quality code.

myisam_sort_buffer_size

Command-Line Format	`--myisam_sort_buffer_size=#`
Option-File Format	`myisam_sort_buffer_size`
Option Sets Variable	Yes, `myisam_sort_buffer_size`
Variable Name	`myisam_sort_buffer_size`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`8388608`
	Range	`4 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`8388608`
	Range	`4 .. 18446744073709547520`

The size of the buffer that is allocated when sorting MyISAM indexes during a REPAIR TABLE or when creating indexes with CREATE INDEX or ALTER TABLE.

The maximum permissible setting for myisam_sort_buffer_size is 4GB. Values larger than 4GB are permitted for 64-bit platforms (except 64-bit Windows, for which large values are truncated to 4GB with a warning).

myisam_stats_method

Command-Line Format	`--myisam_stats_method=name`
Option-File Format	`myisam_stats_method`
Option Sets Variable	Yes, `myisam_stats_method`
Variable Name	`myisam_stats_method`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`enumeration`
	Valid Values	`nulls_equal` `nulls_unequal` `nulls_ignored`

How the server treats NULL values when collecting statistics about the distribution of index values for MyISAM tables. This variable has three possible values, nulls_equal, nulls_unequal, and nulls_ignored. For nulls_equal, all NULL index values are considered equal and form a single value group that has a size equal to the number of NULL values. For nulls_unequal, NULL values are considered unequal, and each NULL forms a distinct value group of size 1. For nulls_ignored, NULL values are ignored.

The method that is used for generating table statistics influences how the optimizer chooses indexes for query execution, as described in , "InnoDB and MyISAM Index Statistics Collection".

myisam_use_mmap

Command-Line Format	`--myisam_use_mmap`
Option-File Format	`myisam_use_mmap`
Option Sets Variable	Yes, `myisam_use_mmap`
Variable Name	`myisam_use_mmap`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`OFF`

Use memory mapping for reading and writing MyISAM tables.

named_pipe

Variable Name named_pipe
Variable Scope Global
Dynamic Variable No
Platform Specific windows
Permitted Values
Type (windows) boolean
Default OFF

(Windows only.) Indicates whether the server supports connections over named pipes.

net_buffer_length

Command-Line Format	`--net_buffer_length=#`
Option-File Format	`net_buffer_length`
Option Sets Variable	Yes, `net_buffer_length`
Variable Name	`net_buffer_length`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`16384`
	Range	`1048576`

Each client thread is associated with a connection buffer and result buffer. Both begin with a size given by net_buffer_length but are dynamically enlarged up to max-allowed-packet bytes as needed. The result buffer shrinks to net_buffer_length after each SQL statement.

This variable should not normally be changed, but if you have very little memory, you can set it to the expected length of statements sent by clients. If statements exceed this length, the connection buffer is automatically enlarged. The maximum value to which net_buffer_length can be set is 1MB.

The session value of this variable is read only.

net_read_timeout

Command-Line Format	`--net_read_timeout=#`
Option-File Format	`net_read_timeout`
Option Sets Variable	Yes, `net_read_timeout`
Variable Name	`net_read_timeout`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`30`
	Min Value	`1`

The number of seconds to wait for more data from a connection before aborting the read. When the server is reading from the client, net_read_timeout is the timeout value controlling when to abort. When the server is writing to the client, net_write_timeout is the timeout value controlling when to abort. See also slave_net_timeout.

net_retry_count

Command-Line Format	`--net_retry_count=#`
Option-File Format	`net_retry_count`
Option Sets Variable	Yes, `net_retry_count`
Variable Name	`net_retry_count`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`10`
	Range	`1 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`10`
	Range	`1 .. 18446744073709547520`

If a read or write on a communication port is interrupted, retry this many times before giving up. This value should be set quite high on FreeBSD because internal interrupts are sent to all threads.

net_write_timeout

Command-Line Format	`--net_write_timeout=#`
Option-File Format	`net_write_timeout`
Option Sets Variable	Yes, `net_write_timeout`
Variable Name	`net_write_timeout`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`60`
	Min Value	`1`

The number of seconds to wait for a block to be written to a connection before aborting the write. See also net_read_timeout.

new

Command-Line Format	`--new`
	`-n`
Option-File Format	`new`
Option Sets Variable	Yes, `new`
Variable Name	`new`
Variable Scope	Global, Session
Dynamic Variable	Yes
Disabled by	`skip-new`
	Permitted Values
	Type	`boolean`
	Default	`FALSE`

This variable was used in MariaDB to turn on some 4.1 behaviors, and is retained for backward compatibility. In MariaDB 5.6, its value is always OFF.

old

Command-Line Format --old
Option-File Format old
Variable Name old
Variable Scope Global
Dynamic Variable No

old is a compatibility variable. It is disabled by default, but can be enabled at startup to revert the server to behaviors present in older versions.
Currently, when old is enabled, it changes the default scope of index hints to that used prior to MariaDB 5.1.17. That is, index hints with no FOR clause apply only to how indexes are used for row retrieval and not to resolution of ORDER BY or GROUP BY clauses. (See , "Index Hint Syntax".) Take care about enabling this in a replication setup. With statement-based binary logging, having different modes for the master and slaves might lead to replication errors.

old_alter_table

Command-Line Format	`--old-alter-table`
Option-File Format	`old-alter-table`
Option Sets Variable	Yes, `old_alter_table`
Variable Name	`old_alter_table`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`OFF`

When this variable is enabled, the server does not use the optimized method of processing an ALTER TABLE operation. It reverts to using a temporary table, copying over the data, and then renaming the temporary table to the original, as used by MariaDB 5.0 and earlier. For more information on the operation of ALTER TABLE, see , "ALTER TABLE Syntax".

old_passwords

Command-Line Format	`--old_passwords`
Option-File Format	`old-passwords`
Option Sets Variable	Yes, `old_passwords`
Variable Name	`old_passwords`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`FALSE`

Whether the server should use pre-4.1-style passwords for MariaDB user accounts. See "Client does not support authentication protocol".

open_files_limit

Command-Line Format	`--open-files-limit=#`
Option-File Format	`open-files-limit`
Option Sets Variable	Yes, `open_files_limit`
Variable Name	`open_files_limit`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`numeric`
	Default	`0`
	Range	`0 .. 65535`

The number of files that the operating system permits mysqld to open. This is the real value permitted by the system and might be different from the value you gave using the --open-files-limit option to mysqld or mysqld_safe. The value is 0 on systems where MariaDB cannot change the number of open files.

optimizer_join_cache_level

Version Introduced	5.6.1
Version Removed	5.6.3
Command-Line Format	`--optimizer_join_cache_level=#`
Option-File Format	`optimizer_join_cache_level`
Option Sets Variable	Yes, `optimizer_join_cache_level`
Variable Name	`optimizer_join_cache_level`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`4`
	Range	`0 .. 4`

Before MariaDB 5.6.3, this variable is used for join buffer management. It controls how join buffers are used for join operations. As of MariaDB 5.6.3, it is removed and the optimizer_switch variable is used instead. See , "Block Nested-Loop and Batched Key Access Joins".

The following table shows the permissible optimizer_join_cache_level values.

Option	Description
`0`	No join buffer is used for any join operation. This setting can be useful for assessing baseline join performance in comparison to performance with nonzero values that enable use of join buffering.
`1`	This is the default value. Join buffers are employed only for inner joins that are executed by the original Block Nested-Loop (BNL) join algorithm. When this algorithm is applied, rows of the inner table are accessed through a table scan, a plain index scan, or a range index scan.
`2`	The server employs an incremental join buffer for a join operation if its first operand is produced by a join operation that uses a join buffer itself.
`3`	The BNL algorithm is used for outer join operations with one inner table and for inner joins.
`4`	The BNL algorithm uses incremental buffers for inner tables. In this case, the BNL algorithm can be used for nested outer joins (outer joins with several inner tables). Such an operation can be executed only if incremental join buffers are used to join all inner tables but the first one.

optimizer_prune_level

Command-Line Format	`--optimizer_prune_level[=#]`
Option-File Format	`optimizer_prune_level`
Option Sets Variable	Yes, `optimizer_prune_level`
Variable Name	`optimizer_prune_level`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`1`

Controls the heuristics applied during query optimization to prune less-promising partial plans from the optimizer search space. A value of 0 disables heuristics so that the optimizer performs an exhaustive search. A value of 1 causes the optimizer to prune plans based on the number of rows retrieved by intermediate plans.

optimizer_search_depth

Command-Line Format	`--optimizer_search_depth[=#]`
Option-File Format	`optimizer_search_depth`
Option Sets Variable	Yes, `optimizer_search_depth`
Variable Name	`optimizer_search_depth`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values (>= 5.6)
	Type	`numeric`
	Default	`62`
	Range	`0 .. 62`

The maximum depth of search performed by the query optimizer. Values larger than the number of relations in a query result in better query plans, but take longer to generate an execution plan for a query. Values smaller than the number of relations in a query return an execution plan quicker, but the resulting plan may be far from being optimal. If set to 0, the system automatically picks a reasonable value.

optimizer_switch

Command-Line Format	`--optimizer_switch=value`
Option-File Format	`optimizer_switch`
	`optimizer_switch`
	`optimizer_switch`
Option Sets Variable	Yes, `optimizer_switch`
Variable Name	`optimizer_switch`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values (>= 5.6.1, <= 5.6.2)
	Type	`set`
	Valid Values	`engine_condition_pushdown={on\|off}` `index_merge={on\|off}` `index_merge_intersection={on\|off}` `index_merge_sort_union={on\|off}` `index_merge_union={on\|off}` `engine_condition_pushdown={on\|off}` `index_condition_pushdown={on\|off}` `mrr={on\|off}` `mrr_cost_based={on\|off}`
	Permitted Values (>= 5.6.3)
	Type	`set`
	Valid Values	`engine_condition_pushdown={on\|off}` `index_merge={on\|off}` `index_merge_intersection={on\|off}` `index_merge_sort_union={on\|off}` `index_merge_union={on\|off}` `engine_condition_pushdown={on\|off}` `index_condition_pushdown={on\|off}` `mrr={on\|off}` `mrr_cost_based={on\|off}` `block_nested_loop={on\|off}` `batched_key_access={on\|off}`

The optimizer_switch system variable enables control over optimizer behavior. The value of this variable is a set of flags, each of which has a value of on or off to indicate whether the corresponding optimizer behavior is enabled or disabled. This variable has global and session values and can be changed at runtime. The global default can be set at server startup.

To see the current set of optimizer flags, select the variable value:

mysql> SELECT @@optimizer_switch\G
*************************** 1. row ***************************
@@optimizer_switch: index_merge=on,index_merge_union=on,
 index_merge_sort_union=on,
 index_merge_intersection=on,
 engine_condition_pushdown=on,
 index_condition_pushdown=on,
 mrr=on,mrr_cost_based=on,
 block_nested_loop=on,batched_key_access=off

For more information about the syntax of this variable and the optimizer behaviors that it controls, see , "Controlling Switchable Optimizations".

optimizer_trace

Version Introduced 5.6.3
Variable Name optimizer_trace
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type string

This variable controls optimizer tracing. For details, see MySQL Internals: Optimizer tracing. This variable was added in MariaDB 5.6.3.
optimizer_trace_features

Version Introduced 5.6.3
Variable Name optimizer_trace_features
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type string

This variable enables or disables selected optimizer tracing features. For details, see MySQL Internals: Optimizer tracing. This variable was added in MariaDB 5.6.3.
optimizer_trace_limit

Version Introduced 5.6.3
Variable Name optimizer_trace_limit
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type numeric
Default 1

The maximum number of optimizer traces to display. For details, see MySQL Internals: Optimizer tracing. This variable was added in MariaDB 5.6.3.
optimizer_trace_max_mem_size

Version Introduced 5.6.3
Variable Name optimizer_trace_max_mem_size
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type numeric
Default 16384

The maximum cumulative size of stored optimizer traces. For details, see MySQL Internals: Optimizer tracing. This variable was added in MariaDB 5.6.3.
optimizer_trace_offset

Version Introduced 5.6.3
Variable Name optimizer_trace_offset
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type numeric
Default -1

The offset of optimizer traces to display. For details, see MySQL Internals: Optimizer tracing. This variable was added in MariaDB 5.6.3.
performance_schema_xxx

Performance Schema system variables are listed in , "Performance Schema System Variables".

pid_file

Command-Line Format	`--pid-file=file_name`
Option-File Format	`pid-file=file_name`
Option Sets Variable	Yes, `pid_file`
Variable Name	`pid_file`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`file name`

The path name of the process ID (PID) file. This variable can be set with the --pid-file option.

plugin_dir

Command-Line Format	`--plugin_dir=path`
Option-File Format	`plugin_dir`
Option Sets Variable	Yes, `plugin_dir`
Variable Name	`plugin_dir`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`directory name`
	Default	`BASEDIR/lib/plugin`

The path name of the plugin directory.

If the plugin directory is writable by the server, it may be possible for a user to write executable code to a file in the directory using SELECT ... INTO DUMPFILE. This can be prevented by making plugin_dir read only to the server or by setting --secure-file-priv to a directory where SELECT writes can be made safely.

port

Command-Line Format	`--port=#`
	`-P`
Option-File Format	`port`
Option Sets Variable	Yes, `port`
Variable Name	`port`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`numeric`
	Default	`3306`

The number of the port on which the server listens for TCP/IP connections. This variable can be set with the --port option.

preload_buffer_size

Command-Line Format	`--preload_buffer_size=#`
Option-File Format	`preload_buffer_size`
Option Sets Variable	Yes, `preload_buffer_size`
Variable Name	`preload_buffer_size`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`32768`
	Range	`1073741824`

The size of the buffer that is allocated when preloading indexes.

profiling
If set to 0 (the default), statement profiling is disabled. If set to 1, statement profiling is enabled and the SHOW PROFILES and SHOW PROFILE statements provide access to profiling information. See , "SHOW PROFILES Syntax".
profiling_history_size
The number of statements for which to maintain profiling information if profiling is enabled. The default value is 15. The maximum value is 100. Setting the value to 0 effectively disables profiling. See , "SHOW PROFILES Syntax".
protocol_version

Variable Name protocol_version
Variable Scope Global
Dynamic Variable No
Permitted Values
Type numeric

The version of the client/server protocol used by the MariaDB server.
proxy_user

Variable Name proxy_user
Variable Scope Session
Dynamic Variable No
Permitted Values
Type string

If the current client is a proxy for another user, this variable is the proxy user account name. Otherwise, this variable is NULL. See , "Proxy Users".
pseudo_thread_id

Variable Name pseudo_thread_id
Variable Scope Session
Dynamic Variable Yes
Permitted Values
Type numeric

This variable is for internal server use.

query_alloc_block_size

Command-Line Format	`--query_alloc_block_size=#`
Option-File Format	`query_alloc_block_size`
Option Sets Variable	Yes, `query_alloc_block_size`
Variable Name	`query_alloc_block_size`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`8192`
	Range	`4294967295`
	Block Size	`1024`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`8192`
	Range	`18446744073709547520`
	Block Size	`1024`

The allocation size of memory blocks that are allocated for objects created during statement parsing and execution. If you have problems with memory fragmentation, it might help to increase this parameter.

query_cache_limit

Command-Line Format	`--query_cache_limit=#`
Option-File Format	`query_cache_limit`
Option Sets Variable	Yes, `query_cache_limit`
Variable Name	`query_cache_limit`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`1048576`
	Range	`0 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`1048576`
	Range	`0 .. 18446744073709547520`

Do not cache results that are larger than this number of bytes. The default value is 1MB.

query_cache_min_res_unit

Command-Line Format	`--query_cache_min_res_unit=#`
Option-File Format	`query_cache_min_res_unit`
Option Sets Variable	Yes, `query_cache_min_res_unit`
Variable Name	`query_cache_min_res_unit`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`4096`
	Range	`4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`4096`
	Range	`18446744073709547520`

The minimum size (in bytes) for blocks allocated by the query cache. The default value is 4096 (4KB). Tuning information for this variable is given in , "Query Cache Configuration".

query_cache_size

Command-Line Format	`--query_cache_size=#`
Option-File Format	`query_cache_size`
Option Sets Variable	Yes, `query_cache_size`
Variable Name	`query_cache_size`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`0`
	Range	`0 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`0`
	Range	`0 .. 18446744073709547520`

The amount of memory allocated for caching query results. The default value is 0, which disables the query cache. To reduce overhead significantly, you should also start the server with query_cache_type=0 if you will not be using the query cache. The permissible values are multiples of 1024; other values are rounded down to the nearest multiple. Note that query-cache-size bytes of memory are allocated even if query_cache_type is set to 0. See , "Query Cache Configuration", for more information.

The query cache needs a minimum size of about 40KB to allocate its structures. (The exact size depends on system architecture.) If you set the value of query_cache_size too small, a warning will occur, as described in , "Query Cache Configuration".

query_cache_type

Command-Line Format	`--query_cache_type=#`
Option-File Format	`query_cache_type`
Option Sets Variable	Yes, `query_cache_type`
Variable Name	`query_cache_type`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`enumeration`
	Default	`1`
	Valid Values	`0` `1` `2`

Set the query cache type. Setting the GLOBAL value sets the type for all clients that connect thereafter. Individual clients can set the SESSION value to affect their own use of the query cache. Possible values are shown in the following table.

Option	Description
`0` or `OFF`	Do not cache results in or retrieve results from the query cache. Note that this does not deallocate the query cache buffer. To do that, you should set `query_cache_size` to 0.
`1` or `ON`	Cache all cacheable query results except for those that begin with `SELECT SQL_NO_CACHE`.
`2` or `DEMAND`	Cache results only for cacheable queries that begin with `SELECT SQL_CACHE`.

This variable defaults to ON.

If the server is started with query_cache_type set to 0, it does not acquire the query cache mutex at all, which means that the query cache cannot be enabled at runtime and there is reduced overhead in query execution.

query_cache_wlock_invalidate

Command-Line Format	`--query_cache_wlock_invalidate`
Option-File Format	`query_cache_wlock_invalidate`
Option Sets Variable	Yes, `query_cache_wlock_invalidate`
Variable Name	`query_cache_wlock_invalidate`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`FALSE`

Normally, when one client acquires a WRITE lock on a MyISAM table, other clients are not blocked from issuing statements that read from the table if the query results are present in the query cache. Setting this variable to 1 causes acquisition of a WRITE lock for a table to invalidate any queries in the query cache that refer to the table. This forces other clients that attempt to access the table to wait while the lock is in effect.

query_prealloc_size

Command-Line Format	`--query_prealloc_size=#`
Option-File Format	`query_prealloc_size`
Option Sets Variable	Yes, `query_prealloc_size`
Variable Name	`query_prealloc_size`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`8192`
	Range	`4294967295`
	Block Size	`1024`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`8192`
	Range	`18446744073709547520`
	Block Size	`1024`

The size of the persistent buffer used for statement parsing and execution. This buffer is not freed between statements. If you are running complex queries, a larger query_prealloc_size value might be helpful in improving performance, because it can reduce the need for the server to perform memory allocation during query execution operations.

rand_seed1
The rand-seed1 and rand_seed2 variables exist as session variables only, and can be set but not read. The variables-but not their values-are shown in the output of SHOW VARIABLES.
The purpose of these variables is to support replication of the RAND() function. For statements that invoke RAND(), the master passes two values to the slave, where they are used to seed the random number generator. The slave uses these values to set the session variables rand_seed1 and rand-seed2 so that RAND() on the slave generates the same value as on the master.
rand_seed2
See the description for rand_seed1.

range_alloc_block_size

Command-Line Format	`--range_alloc_block_size=#`
Option-File Format	`range_alloc_block_size`
Option Sets Variable	Yes, `range_alloc_block_size`
Variable Name	`range_alloc_block_size`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`4096`
	Range	`4294967295`
	Block Size	`1024`

The size of blocks that are allocated when doing range optimization.

read_buffer_size

Command-Line Format	`--read_buffer_size=#`
Option-File Format	`read_buffer_size`
Option Sets Variable	Yes, `read_buffer_size`
Variable Name	`read_buffer_size`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`131072`
	Range	`2147479552`

Each thread that does a sequential scan for a MyISAM table allocates a buffer of this size (in bytes) for each table it scans. If you do many sequential scans, you might want to increase this value, which defaults to 131072. The value of this variable should be a multiple of 4KB. If it is set to a value that is not a multiple of 4KB, its value will be rounded down to the nearest multiple of 4KB.

The maximum permissible setting for read_buffer_size is 2GB.

For more information about memory use during different operations, see , "How MariaDB Uses Memory".

read_only

Command-Line Format	`--read-only`
Option-File Format	`read_only`
Option Sets Variable	Yes, `read_only`
Variable Name	`read_only`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`0`

This variable is off by default. When it is enabled, the server permits no updates except from users that have the SUPER privilege or (on a slave server) from updates performed by slave threads. In replication setups, it can be useful to enable read_only on slave servers to ensure that slaves accept updates only from the master server and not from clients.

read_only does not apply to TEMPORARY tables, nor does it prevent the server from inserting rows into the log tables (see , "Selecting General Query and Slow Query Log Output Destinations"). This variable does not prevent the use of ANALYZE TABLE or OPTIMIZE TABLE statements because its purpose is to prevent changes to table structure or contents. Analysis and optimization do not qualify as such changes. This means, for example, that consistency checks on read-only slaves can be performed with mysqlcheck --all-databases --analyze.

read_only exists only as a GLOBAL variable, so changes to its value require the SUPER privilege. Changes to read_only on a master server are not replicated to slave servers. The value can be set on a slave server independent of the setting on the master.Important

In MariaDB 5.6, enabling read_only prevents the use of the SET PASSWORD statement by any user not having the SUPER privilege. This is not necessarily the case for all MariaDB release series. When replicating from one MariaDB release series to another (for example, from a MariaDB 5.0 master to a MariaDB 5.1 or later slave), you should check the documentation for the versions running on both master and slave to determine whether the behavior of read_only in this regard is or is not the same, and, if it is different, whether this has an impact on your applications.

The following conditions apply:

If you attempt to enable read-only while you have any explicit locks (acquired with LOCK TABLES) or have a pending transaction, an error occurs.
If you attempt to enable read_only while other clients hold explicit table locks or have pending transactions, the attempt blocks until the locks are released and the transactions end. While the attempt to enable read_only is pending, requests by other clients for table locks or to begin transactions also block until read_only has been set.
read-only can be enabled while you hold a global read lock (acquired with FLUSH TABLES WITH READ LOCK) because that does not involve table locks.

In MariaDB 5.6, attempts to set read_only block for active transactions that hold metadata locks until those transactions end.

read_rnd_buffer_size

Command-Line Format	`--read_rnd_buffer_size=#`
Option-File Format	`read_rnd_buffer_size`
Option Sets Variable	Yes, `read_rnd_buffer_size`
Variable Name	`read_rnd_buffer_size`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`262144`
	Range	`4294967295`

When reading rows from a MyISAM table in sorted order following a key-sorting operation, the rows are read through this buffer to avoid disk seeks. See , "ORDER BY Optimization". Setting the variable to a large value can improve ORDER BY performance by a lot. However, this is a buffer allocated for each client, so you should not set the global variable to a large value. Instead, change the session variable only from within those clients that need to run large queries.

The maximum permissible setting for read_rnd_buffer_size is 2GB.

For more information about memory use during different operations, see , "How MariaDB Uses Memory".

relay_log_purge

Command-Line Format	`--relay_log_purge`
Option-File Format	`relay_log_purge`
Option Sets Variable	Yes, `relay_log_purge`
Variable Name	`relay_log_purge`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`TRUE`

Disables or enables automatic purging of relay log files as soon as they are not needed any more. The default value is 1 (ON).

relay_log_space_limit

Command-Line Format	`--relay_log_space_limit=#`
Option-File Format	`relay_log_space_limit`
Option Sets Variable	Yes, `relay_log_space_limit`
Variable Name	`relay_log_space_limit`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`0`
	Range	`0 .. 4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`0`
	Range	`0 .. 18446744073709547520`

The maximum amount of space to use for all relay logs.

report_host

Command-Line Format	`--report-host=host_name`
Option-File Format	`report-host`
Option Sets Variable	Yes, `report_host`
Variable Name	`report-host`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`string`

The value of the --report-host option.

report_password

Command-Line Format	`--report-password=name`
Option-File Format	`report-password`
Option Sets Variable	Yes, `report_password`
Variable Name	`report-password`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`string`

The value of the --report-password option. Not the same as the password used for the MariaDB replication user account.

report_port

Command-Line Format	`--report-port=#`
Option-File Format	`report-port`
Option Sets Variable	Yes, `report_port`
Variable Name	`report-port`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values (>= 5.6.5)
	Type	`numeric`
	Default	`0`

The value of the --report-port option.

report_user

Command-Line Format	`--report-user=name`
Option-File Format	`report-user`
Option Sets Variable	Yes, `report_user`
Variable Name	`report-user`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`string`

The value of the --report-user option. Not the same as the name for the MariaDB replication user account.

rpl_semi_sync_master_enabled

Variable Name rpl_semi_sync_master_enabled
Variable Scope Global
Dynamic Variable Yes
Permitted Values
Type boolean
Default OFF

Controls whether semisynchronous replication is enabled on the master. To enable or disable the plugin, set this variable to ON or OFF (or 1 or 0), respectively. The default is OFF.
This variable is available only if the master-side semisynchronous replication plugin is installed.
rpl_semi_sync_master_timeout

Variable Name rpl_semi_sync_master_timeout
Variable Scope Global
Dynamic Variable Yes
Permitted Values
Type numeric
Default 10000

A value in milliseconds that controls how long the master waits on a commit for acknowledgment from a slave before timing out and reverting to asynchronous replication. The default value is 10000 (10 seconds).
This variable is available only if the master-side semisynchronous replication plugin is installed.
rpl_semi_sync_master_trace_level

Variable Name rpl_semi_sync_master_trace_level
Variable Scope Global
Dynamic Variable Yes
Permitted Values
Type numeric
Default 32

The semisynchronous replication debug trace level on the master. Currently, four levels are defined:
- 1 = general level (for example, time function failures)
- = detail level (more verbose information)
- = net wait level (more information about network waits)
- = function level (information about function entry and exit)
This variable is available only if the master-side semisynchronous replication plugin is installed.
rpl_semi_sync_master_wait_no_slave

Variable Name rpl_semi_sync_master_wait_no_slave
Variable Scope Global
Dynamic Variable Yes
Permitted Values
Type boolean
Default ON

With semisynchronous replication, for each transaction, the master waits until timeout for acknowledgment of receipt from some semisynchronous slave. If no response occurs during this period, the master reverts to normal replication. This variable controls whether the master waits for the timeout to expire before reverting to normal replication even if the slave count drops to zero during the timeout period.
If the value is ON (the default), it is permissible for the slave count to drop to zero during the timeout period (for example, if slaves disconnect). The master still waits for the timeout, so as long as some slave reconnects and acknowledges the transaction within the timeout interval, semisynchronous replication continues.
If the value is OFF, the master reverts to normal replication if the slave count drops to zero during the timeout period.
This variable is available only if the master-side semisynchronous replication plugin is installed.
rpl_semi_sync_slave_enabled

Variable Name rpl_semi_sync_slave_enabled
Variable Scope Global
Dynamic Variable Yes
Permitted Values
Type boolean
Default OFF

Controls whether semisynchronous replication is enabled on the slave. To enable or disable the plugin, set this variable to ON or OFF (or 1 or 0), respectively. The default is OFF.
This variable is available only if the slave-side semisynchronous replication plugin is installed.
rpl_semi_sync_slave_trace_level

Variable Name rpl_semi_sync_slave_trace_level
Variable Scope Global
Dynamic Variable Yes
Permitted Values
Type numeric
Default 32

The semisynchronous replication debug trace level on the slave. See rpl_semi_sync_master_trace_level for the permissible values.
This variable is available only if the slave-side semisynchronous replication plugin is installed.

secure_auth

Command-Line Format	`--secure-auth`
Option-File Format	`secure-auth`
Option Sets Variable	Yes, `secure_auth`
Variable Name	`secure_auth`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values (<= 5.6.4)
	Type	`boolean`
	Default	`OFF`
	Permitted Values (>= 5.6.5)
	Type	`boolean`
	Default	`ON`

If this variable is enabled, the server blocks connections by clients that attempt to use accounts that have passwords stored in the old (pre-4.1) format.

Enable this variable to prevent all use of passwords employing the old format (and hence insecure communication over the network). Before MariaDB 5.6.5, this variable is disabled by default. As of MariaDB 5.6.5, it is enabled by default.

Server startup fails with an error if this variable is enabled and the privilege tables are in pre-4.1 format. See "Client does not support authentication protocol".

secure_file_priv

Command-Line Format	`--secure-file-priv=path`
Option-File Format	`secure-file-priv=path`
Option Sets Variable	Yes, `secure_file_priv`
Variable Name	`secure-file-priv`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`string`

By default, this variable is empty. If set to the name of a directory, it limits the effect of the LOAD-FILE() function and the LOAD DATA and SELECT ... INTO OUTFILE statements to work only with files in that directory.

server_id

Command-Line Format	`--server-id=#`
Option-File Format	`server-id`
Option Sets Variable	Yes, `server_id`
Variable Name	`server_id`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`0`
	Range	`0 .. 4294967295`

The server ID, used in replication to give each master and slave a unique identity. This variable is set by the --server-id option. For each server participating in replication, you should pick a positive integer in the range from 1 to 2³² - 1 to act as that server's ID.

shared_memory

Variable Name shared_memory
Variable Scope Global
Dynamic Variable No
Platform Specific windows

(Windows only.) Whether the server permits shared-memory connections.
shared_memory_base_name

Variable Name shared_memory_base_name
Variable Scope Global
Dynamic Variable No
Platform Specific windows

(Windows only.) The name of shared memory to use for shared-memory connections. This is useful when running multiple MariaDB instances on a single physical machine. The default name is MariaDB. The name is case sensitive.
skip_external_locking
This is OFF if mysqld uses external locking, ON if external locking is disabled. This affects only MyISAM table access.
skip_name_resolve
This variable is set from the value of the --skip-name-resolve option. If it is ON, mysqld resolves host names when checking client connections. If OFF, mysqld uses only IP numbers and all Host column values in the grant tables must be IP addresses or localhost. See , "DNS Lookup Optimization and the Host Cache".
skip_networking
This is ON if the server permits only local (non-TCP/IP) connections. On Unix, local connections use a Unix socket file. On Windows, local connections use a named pipe or shared memory. This variable can be set to ON with the --skip-networking option.
skip_show_database
This prevents people from using the SHOW DATABASES statement if they do not have the SHOW DATABASES privilege. This can improve security if you have concerns about users being able to see databases belonging to other users. Its effect depends on the SHOW DATABASES privilege: If the variable value is ON, the SHOW DATABASES statement is permitted only to users who have the SHOW DATABASES privilege, and the statement displays all database names. If the value is OFF, SHOW DATABASES is permitted to all users, but displays the names of only those databases for which the user has the SHOW DATABASES or other privilege.

slow_launch_time

Command-Line Format	`--slow_launch_time=#`
Option-File Format	`slow_launch_time`
Option Sets Variable	Yes, `slow_launch_time`
Variable Name	`slow_launch_time`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`2`

If creating a thread takes longer than this many seconds, the server increments the Slow_launch_threads status variable.

slow_query_log

Command-Line Format	`--slow-query-log`
Option-File Format	`slow-query-log`
Option Sets Variable	Yes, `slow_query_log`
Variable Name	`slow_query_log`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`OFF`

Whether the slow query log is enabled. The value can be 0 (or OFF) to disable the log or 1 (or ON) to enable the log. The default value depends on whether the --slow_query_log option is given. The destination for log output is controlled by the log_output system variable; if that value is NONE, no log entries are written even if the log is enabled.

"Slow" is determined by the value of the long-query-time variable. See , "The Slow Query Log".

slow_query_log_file

Command-Line Format	`--slow-query-log-file=file_name`
Option-File Format	`slow_query_log_file`
Option Sets Variable	Yes, `slow_query_log_file`
Variable Name	`slow_query_log_file`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`file name`

The name of the slow query log file. The default value is host_name-slow.log, but the initial value can be changed with the --slow_query_log_file option.

socket

Command-Line Format	`--socket=name`
Option-File Format	`socket`
Option Sets Variable	Yes, `socket`
Variable Name	`socket`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`file name`
	Default	`/tmp/mysql.sock`

On Unix platforms, this variable is the name of the socket file that is used for local client connections. The default is /tmp/mysql.sock. (For some distribution formats, the directory might be different, such as /var/lib/mysql for RPMs.)

On Windows, this variable is the name of the named pipe that is used for local client connections. The default value is MariaDB (not case sensitive).

sort_buffer_size

Command-Line Format	`--sort_buffer_size=#`
Option-File Format	`sort_buffer_size`
Option Sets Variable	Yes, `sort_buffer_size`
Variable Name	`sort_buffer_size`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`2097144`
	Max Value	`4294967295`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`2097144`
	Max Value	`18446744073709547520`

Each session that needs to do a sort allocates a buffer of this size. sort_buffer_size is not specific to any storage engine and applies in a general manner for optimization. See , "ORDER BY Optimization", for example.

If you see many Sort-merge-passes per second in SHOW GLOBAL STATUS output, you can consider increasing the sort_buffer_size value to speed up ORDER BY or GROUP BY operations that cannot be improved with query optimization or improved indexing. The entire buffer is allocated even if it is not all needed, so setting it larger than required globally will slow down most queries that sort. It is best to increase it as a session setting, and only for the sessions that need a larger size. On Linux, there are thresholds of 256KB and 2MB where larger values may significantly slow down memory allocation, so you should consider staying below one of those values. Experiment to find the best value for your workload. See "Where MariaDB Stores Temporary Files".

The maximum permissible setting for sort_buffer_size is 4GB. Values larger than 4GB are permitted for 64-bit platforms (except 64-bit Windows, for which large values are truncated to 4GB with a warning).

sql_auto_is_null

Variable Name sql_auto_is_null
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type boolean
Default 0

If this variable is set to 1, then after a statement that successfully inserts an automatically generated AUTO_INCREMENT value, you can find that value by issuing a statement of the following form:
```
SELECT * FROM tbl_name WHERE auto_col IS NULL
```
If the statement returns a row, the value returned is the same as if you invoked the LAST_INSERT_ID() function. For details, including the return value after a multiple-row insert, see , "Information Functions". If no AUTO_INCREMENT value was successfully inserted, the SELECT statement returns no row.
The behavior of retrieving an AUTO_INCREMENT value by using an IS NULL comparison is used by some ODBC programs, such as Access. See , "Obtaining Auto-Increment Values". This behavior can be disabled by setting sql_auto_is_null to 0.
The default value of sql_auto_is_null is 0 in MariaDB 5.6.
sql_big_selects

Variable Name sql_big_selects
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type boolean
Default 1

If set to 0, MariaDB aborts SELECT statements that are likely to take a very long time to execute (that is, statements for which the optimizer estimates that the number of examined rows exceeds the value of max_join_size). This is useful when an inadvisable WHERE statement has been issued. The default value for a new connection is 1, which permits all SELECT statements.
If you set the max_join_size system variable to a value other than DEFAULT, sql_big_selects is set to 0.
sql_buffer_result

Variable Name sql_buffer_result
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type boolean
Default 0

If set to 1, sql-buffer-result forces results from SELECT statements to be put into temporary tables. This helps MariaDB free the table locks early and can be beneficial in cases where it takes a long time to send results to the client. The default value is 0.
sql_log_bin

Variable Name sql_log_bin
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type boolean

This variable controls whether logging to the binary log is done. The default value is 1 (do logging). To change logging for the current session, change the session value of this variable. The session user must have the SUPER privilege to set this variable.
In MariaDB 5.6, it is not possible to set @@session.sql_log_bin within a transaction or subquery. (Bug #53437)
sql_log_off

Variable Name sql_log_off
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type boolean
Default 0

This variable controls whether logging to the general query log is done. The default value is 0 (do logging). To change logging for the current session, change the session value of this variable. The session user must have the SUPER privilege to set this option. The default value is 0.

sql_mode

Variable Name	`sql_log_update`
Variable Scope	Session
Dynamic Variable	Yes
Deprecated	5.0, by `sql_log_bin`
	Permitted Values
	Type	`boolean`

Command-Line Format	`--sql-mode=name`
Option-File Format	`sql-mode`
Option Sets Variable	Yes, `sql_mode`
Variable Name	`sql_mode`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`set`
	Default	`''`
	Valid Values	`ALLOW_INVALID_DATES` `ANSI_QUOTES` `ERROR_FOR_DIVISION_BY_ZERO` `HIGH_NOT_PRECEDENCE` `IGNORE_SPACE` `NO_AUTO_CREATE_USER` `NO_AUTO_VALUE_ON_ZERO` `NO_BACKSLASH_ESCAPES` `NO_DIR_IN_CREATE` `NO_ENGINE_SUBSTITUTION` `NO_FIELD_OPTIONS` `NO_KEY_OPTIONS` `NO_TABLE_OPTIONS` `NO_UNSIGNED_SUBTRACTION` `NO_ZERO_DATE` `NO_ZERO_IN_DATE` `ONLY_FULL_GROUP_BY` `PAD_CHAR_TO_FULL_LENGTH` `PIPES_AS_CONCAT` `REAL_AS_FLOAT` `STRICT_ALL_TABLES` `STRICT_TRANS_TABLES`

The current server SQL mode, which can be set dynamically. See , "Server SQL Modes".

sql_notes
If set to 1 (the default), warnings of Note level increment warning_count and the server records them. If set to 0, Note warnings do not increment warning_count and the server does not record them. mysqldump includes output to set this variable to 0 so that reloading the dump file does not produce warnings for events that do not affect the integrity of the reload operation.
sql_quote_show_create
If set to 1 (the default), the server quotes identifiers for SHOW CREATE TABLE and SHOW CREATE DATABASE statements. If set to 0, quoting is disabled. This option is enabled by default so that replication works for identifiers that require quoting. See , "SHOW CREATE TABLE Syntax", and , "SHOW CREATE DATABASE Syntax".
sql_safe_updates
If set to 1, MariaDB aborts UPDATE or DELETE statements that do not use a key in the WHERE clause or a LIMIT clause. This makes it possible to catch UPDATE or DELETE statements where keys are not used properly and that would probably change or delete a large number of rows. The default value is 0.
sql_select_limit

Variable Name sql_select_limit
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type numeric

The maximum number of rows to return from SELECT statements. The default value for a new connection is the maximum number of rows that the server permits per table. Typical default values are (2³²)-1 or (2⁶⁴)-1. If you have changed the limit, the default value can be restored by assigning a value of DEFAULT.
If a SELECT has a LIMIT clause, the LIMIT takes precedence over the value of sql_select_limit.
sql-select-limit does not apply to SELECT statements executed within stored routines. It also does not apply to SELECT statements that do not produce a result set to be returned to the client. These include SELECT statements in subqueries, CREATE TABLE ... SELECT, and INSERT INTO ... SELECT.
sql_warnings
This variable controls whether single-row INSERT statements produce an information string if warnings occur. The default is 0. Set the value to 1 to produce an information string.

ssl_ca

Command-Line Format	`--ssl-ca=name`
Option-File Format	`ssl-ca`
Option Sets Variable	Yes, `ssl_ca`
Variable Name	`ssl-ca`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`file name`

The path to a file with a list of trusted SSL CAs.

ssl_capath

Command-Line Format	`--ssl-capath=name`
Option-File Format	`ssl-capath`
Option Sets Variable	Yes, `ssl_capath`
Variable Name	`ssl-capath`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`directory name`

The path to a directory that contains trusted SSL CA certificates in PEM format.

ssl_cert

Command-Line Format	`--ssl-cert=name`
Option-File Format	`ssl-cert`
Option Sets Variable	Yes, `ssl_cert`
Variable Name	`ssl-cert`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`file name`

The name of the SSL certificate file to use for establishing a secure connection.

ssl_cipher

Command-Line Format	`--ssl-cipher=name`
Option-File Format	`ssl-cipher`
Option Sets Variable	Yes, `ssl_cipher`
Variable Name	`ssl-cipher`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`file name`

A list of permissible ciphers to use for SSL encryption.

ssl_crl

Version Introduced	5.6.3
Command-Line Format	`--ssl-crl=name`
Option-File Format	`ssl-crl`
Option Sets Variable	Yes, `ssl_crl`
Variable Name	`ssl-crl`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`file name`

The path to a file containing certificate revocation lists in PEM format. Revocation lists work for MariaDB distributions compiled against OpenSSL (but not yaSSL).

This variable was added in MariaDB 5.6.3.

ssl_crlpath

Version Introduced	5.6.3
Command-Line Format	`--ssl-crlpath=name`
Option-File Format	`ssl-crlpath`
Option Sets Variable	Yes, `ssl_crlpath`
Variable Name	`ssl-crlpath`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`directory name`

The path to a directory that contains files containing certificate revocation lists in PEM format. Revocation lists work for MariaDB distributions compiled against OpenSSL (but not yaSSL).

This variable was added in MariaDB 5.6.3.

ssl_key

Command-Line Format	`--ssl-key=name`
Option-File Format	`ssl-key`
Option Sets Variable	Yes, `ssl_key`
Variable Name	`ssl-key`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`string`

The name of the SSL key file to use for establishing a secure connection.

storage_engine

Variable Name storage_engine
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type enumeration
Default InnoDB

The default storage engine (table type). To set the storage engine at server startup, use the --default-storage-engine option. See , "Server Command Options".
This variable is deprecated. Use default_storage_engine instead.

sync_frm

Command-Line Format	`--sync-frm`
Option-File Format	`sync_frm`
Option Sets Variable	Yes, `sync_frm`
Variable Name	`sync_frm`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`TRUE`

If this variable is set to 1, when any nontemporary table is created its .frm file is synchronized to disk (using fdatasync()). This is slower but safer in case of a crash. The default is 1.

system_time_zone

Variable Name system_time_zone
Variable Scope Global
Dynamic Variable No
Permitted Values
Type string

The server system time zone. When the server begins executing, it inherits a time zone setting from the machine defaults, possibly modified by the environment of the account used for running the server or the startup script. The value is used to set system_time_zone. Typically the time zone is specified by the TZ environment variable. It also can be specified using the --timezone option of the mysqld_safe script.
The system-time-zone variable differs from time_zone. Although they might have the same value, the latter variable is used to initialize the time zone for each client that connects. See , "MySQL Server Time Zone Support".

table_definition_cache

Command-Line Format	`--table_definition_cache=#`
Option-File Format	`table_definition_cache`
Option Sets Variable	Yes, `table_definition_cache`
Variable Name	`table_definition_cache`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`400`
	Range	`524288`

The number of table definitions that can be stored in the definition cache. If you use a large number of tables, you can create a large table definition cache to speed up opening of tables. The table definition cache takes less space and does not use file descriptors, unlike the normal table cache. The minimum and default values are both 400.

table_open_cache

Command-Line Format	`--table-open-cache=#`
Option-File Format	`table_open_cache`
Variable Name	`table_open_cache`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`400`
	Range	`524288`

The number of open tables for all threads. Increasing this value increases the number of file descriptors that mysqld requires. You can check whether you need to increase the table cache by checking the Opened_tables status variable. See , "Server Status Variables". If the value of Opened_tables is large and you do not use FLUSH TABLES often (which just forces all tables to be closed and reopened), then you should increase the value of the table-open-cache variable. For more information about the table cache, see , "How MariaDB Opens and Closes Tables".

thread_cache_size

Command-Line Format	`--thread_cache_size=#`
Option-File Format	`thread_cache_size`
Option Sets Variable	Yes, `thread_cache_size`
Variable Name	`thread_cache_size`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`0`
	Range	`0 .. 16384`

How many threads the server should cache for reuse. When a client disconnects, the client's threads are put in the cache if there are fewer than thread_cache_size threads there. Requests for threads are satisfied by reusing threads taken from the cache if possible, and only when the cache is empty is a new thread created. This variable can be increased to improve performance if you have a lot of new connections. Normally, this does not provide a notable performance improvement if you have a good thread implementation. However, if your server sees hundreds of connections per second you should normally set thread_cache_size high enough so that most new connections use cached threads. By examining the difference between the Connections and Threads_created status variables, you can see how efficient the thread cache is. For details, see , "Server Status Variables".

thread_concurrency

Version Deprecated	5.6.1
Command-Line Format	`--thread_concurrency=#`
Option-File Format	`thread_concurrency`
Option Sets Variable	Yes, `thread_concurrency`
Variable Name	`thread_concurrency`
Variable Scope	Global
Dynamic Variable	No
Deprecated	5.6.1
	Permitted Values
	Type	`numeric`
	Default	`10`
	Range	`1 .. 512`

This variable is specific to Solaris systems, for which mysqld invokes the thr_setconcurrency() with the variable value. This function enables applications to give the threads system a hint about the desired number of threads that should be run at the same time.

This variable is deprecated as of MariaDB 5.6.1 and will be removed in a future MariaDB release.

thread_handling

Command-Line Format	`--thread_handling=name`
Option-File Format	`thread_handling=name`
Option Sets Variable	Yes, `thread_handling`
Variable Name	`thread_handling`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`enumeration`
	Valid Values	`no-threads` `one-thread-per-connection` `dynamically-loaded`

The thread-handling model used by the server for connection threads. The permissible values are no-threads (the server uses a single thread) and one-thread-per-connection (the server uses one thread to handle each client connection). no-threads is useful for debugging under Linux; see MySQL Internals: Porting.

thread_stack

Command-Line Format	`--thread_stack=#`
Option-File Format	`thread_stack`
Option Sets Variable	Yes, `thread_stack`
Variable Name	`thread_stack`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`196608`
	Range	`4294967295`
	Block Size	`1024`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`262144`
	Range	`18446744073709547520`
	Block Size	`1024`

The stack size for each thread. Many of the limits detected by the crash-me test are dependent on this value. See , "The MariaDB Benchmark Suite". The default of 192KB (256KB for 64-bit systems) is large enough for normal operation. If the thread stack size is too small, it limits the complexity of the SQL statements that the server can handle, the recursion depth of stored procedures, and other memory-consuming actions.

time_format
This variable is unused.

time_zone

Command-Line Format	`--default_time_zone=string`
Option-File Format	`default_time_zone`
Variable Name	`time_zone`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`string`

The current time zone. This variable is used to initialize the time zone for each client that connects. By default, the initial value of this is 'SYSTEM' (which means, "use the value of system_time_zone"). The value can be specified explicitly at server startup with the --default-time-zone option. See , "MySQL Server Time Zone Support".

timed_mutexes

Command-Line Format	`--timed_mutexes`
Option-File Format	`timed_mutexes`
Option Sets Variable	Yes, `timed_mutexes`
Variable Name	`timed_mutexes`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`OFF`

This variable controls whether InnoDB mutexes are timed. If this variable is set to 0 or OFF (the default), mutex timing is disabled. If the variable is set to 1 or ON, mutex timing is enabled. With timing enabled, the os_wait_times value in the output from SHOW ENGINE INNODB MUTEX indicates the amount of time (in ms) spent in operating system waits. Otherwise, the value is 0.

timestamp = {timestamp_value | DEFAULT}
Set the time for this client. This is used to get the original timestamp if you use the binary log to restore rows. timestamp_value should be a Unix epoch timestamp, not a MariaDB timestamp.
As of MariaDB 5.6.4, timestamp is a DOUBLE rather than BIGINT because its value includes a microseconds part.
SET timestamp affects the value returned by NOW() but not by SYSDATE(). This means that timestamp settings in the binary log have no effect on invocations of SYSDATE(). The server can be started with the --sysdate-is-now option to cause SYSDATE() to be an alias for NOW(), in which case SET timestamp affects both functions.

tmp_table_size

Command-Line Format	`--tmp_table_size=#`
Option-File Format	`tmp_table_size`
Option Sets Variable	Yes, `tmp_table_size`
Variable Name	`tmp_table_size`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`system dependent`
	Range	`4294967295`

The maximum size of internal in-memory temporary tables. (The actual limit is determined as the minimum of tmp_table_size and max_heap_table_size.) If an in-memory temporary table exceeds the limit, MariaDB automatically converts it to an on-disk MyISAM table. Increase the value of tmp-table-size (and max_heap_table_size if necessary) if you do many advanced GROUP BY queries and you have lots of memory. This variable does not apply to user-created MEMORY tables.

You can compare the number of internal on-disk temporary tables created to the total number of internal temporary tables created by comparing the values of the Created_tmp_disk_tables and Created_tmp_tables variables.

tmpdir

Command-Line Format	`--tmpdir=path`
	`-t`
Option-File Format	`tmpdir`
Option Sets Variable	Yes, `tmpdir`
Variable Name	`tmpdir`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`file name`

The directory used for temporary files and temporary tables. This variable can be set to a list of several paths that are used in round-robin fashion. Paths should be separated by colon characters (":") on Unix and semicolon characters (";") on Windows.

The multiple-directory feature can be used to spread the load between several physical disks. If the MariaDB server is acting as a replication slave, you should not set tmpdir to point to a directory on a memory-based file system or to a directory that is cleared when the server host restarts. A replication slave needs some of its temporary files to survive a machine restart so that it can replicate temporary tables or LOAD DATA INFILE operations. If files in the temporary file directory are lost when the server restarts, replication fails. You can set the slave's temporary directory using the slave_load_tmpdir variable. In that case, the slave will not use the general tmpdir value and you can set tmpdir to a nonpermanent location.

transaction_alloc_block_size

Command-Line Format	`--transaction_alloc_block_size=#`
Option-File Format	`transaction_alloc_block_size`
Option Sets Variable	Yes, `transaction_alloc_block_size`
Variable Name	`transaction_alloc_block_size`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`8192`
	Range	`4294967295`
	Block Size	`1024`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`8192`
	Range	`18446744073709547520`
	Block Size	`1024`

The amount in bytes by which to increase a per-transaction memory pool which needs memory. See the description of transaction_prealloc_size.

transaction_prealloc_size

Command-Line Format	`--transaction_prealloc_size=#`
Option-File Format	`transaction_prealloc_size`
Option Sets Variable	Yes, `transaction_prealloc_size`
Variable Name	`transaction_prealloc_size`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Platform Bit Size	`32`
	Type	`numeric`
	Default	`4096`
	Range	`4294967295`
	Block Size	`1024`
	Permitted Values
	Platform Bit Size	`64`
	Type	`numeric`
	Default	`4096`
	Range	`18446744073709547520`
	Block Size	`1024`

There is a per-transaction memory pool from which various transaction-related allocations take memory. The initial size of the pool in bytes is transaction_prealloc_size. For every allocation that cannot be satisfied from the pool because it has insufficient memory available, the pool is increased by transaction_alloc_block_size bytes. When the transaction ends, the pool is truncated to transaction_prealloc_size bytes.

By making transaction_prealloc_size sufficiently large to contain all statements within a single transaction, you can avoid many malloc() calls.

tx_isolation

Variable Name	`tx_isolation`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`enumeration`
	Default	`REPEATABLE-READ`
	Valid Values	`READ-UNCOMMITTED` `READ-COMMITTED` `REPEATABLE-READ` `SERIALIZABLE`

The default transaction isolation level. Defaults to REPEATABLE-READ.

This variable can be set directly, or indirectly using the SET TRANSACTION statement. See , "SET TRANSACTION Syntax". If you set tx_isolation directly to an isolation level name that contains a space, the name should be enclosed within quotation marks, with the space replaced by a dash. For example:

SET tx_isolation = 'READ-COMMITTED';

Any unique prefix of a valid value may be used to set the value of this variable.

The default transaction isolation level can also be set at startup using the --transaction-isolation server option.

tx_read_only

Version Introduced 5.6.5
Variable Name tx_read_only
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type boolean

The default transaction access mode. The value can be OFF (read/write, the default) or ON (read only).
This variable can be set directly, or indirectly using the SET TRANSACTION statement. See , "SET TRANSACTION Syntax".
To set the default transaction access mode at startup, use the --transaction-read-only server option.
This variable was added in MariaDB 5.6.5.
unique_checks

Variable Name unique_checks
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type boolean
Default 1

If set to 1 (the default), uniqueness checks for secondary indexes in InnoDB tables are performed. If set to 0, storage engines are permitted to assume that duplicate keys are not present in input data. If you know for certain that your data does not contain uniqueness violations, you can set this to 0 to speed up large table imports to InnoDB.
Note that setting this variable to 0 does not require storage engines to ignore duplicate keys. An engine is still permitted to check for them and issue duplicate-key errors if it detects them.

updatable_views_with_limit

Command-Line Format	`--updatable_views_with_limit=#`
Option-File Format	`updatable_views_with_limit`
Option Sets Variable	Yes, `updatable_views_with_limit`
Variable Name	`updatable_views_with_limit`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`1`

This variable controls whether updates to a view can be made when the view does not contain all columns of the primary key defined in the underlying table, if the update statement contains a LIMIT clause. (Such updates often are generated by GUI tools.) An update is an UPDATE or DELETE statement. Primary key here means a PRIMARY KEY, or a UNIQUE index in which no column can contain NULL.

The variable can have two values:

1 or YES: Issue a warning only (not an error message). This is the default value.
0 or NO: Prohibit the update.

version
The version number for the server. The value might also include a suffix indicating server build or configuration information. -log indicates that one or more of the general log, slow query log, or binary log are enabled. -debug indicates that the server was built with debugging support enabled.
version_comment

Variable Name version_comment
Variable Scope Global
Dynamic Variable No
Permitted Values
Type string

The CMake configuration program has a WITH_COMMENT option that permits a comment to be specified when building MySQL. This variable contains the value of that comment. See , "MySQL Source-Configuration Options".
version_compile_machine

Variable Name version_compile_machine
Variable Scope Global
Dynamic Variable No
Permitted Values
Type string

The type of machine or architecture on which MariaDB was built.
version_compile_os

Variable Name version_compile_os
Variable Scope Global
Dynamic Variable No
Permitted Values
Type string

The type of operating system on which MariaDB was built.

wait_timeout

Command-Line Format	`--wait_timeout=#`
Option-File Format	`wait_timeout`
Option Sets Variable	Yes, `wait_timeout`
Variable Name	`wait_timeout`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`28800`
	Range	`1 .. 31536000`
	Permitted Values
	Type (windows)	`numeric`
	Default	`28800`
	Range	`1 .. 2147483`

The number of seconds the server waits for activity on a noninteractive connection before closing it.

On thread startup, the session wait-timeout value is initialized from the global wait_timeout value or from the global interactive_timeout value, depending on the type of client (as defined by the CLIENT_INTERACTIVE connect option to mysql_real_connect()). See also interactive_timeout.

warning_count
The number of errors, warnings, and notes that resulted from the last statement that generated messages. This variable is read only. See , "SHOW WARNINGS Syntax".

Variable Name	`automatic_sp_privileges`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`TRUE`

Variable Name	`character_set_client`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`string`

Variable Name	`character_set_connection`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`string`

Variable Name	`character_set_results`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`string`

Variable Name	`character_set_system`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`string`

Variable Name	`collation_connection`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`string`

Variable Name	`debug_sync`
Variable Scope	Session
Dynamic Variable	Yes
	Permitted Values
	Type	`string`

Variable Name	`external_user`
Variable Scope	Session
Dynamic Variable	No
	Permitted Values
	Type	`string`

Command-Line Format	`--flush`
Option-File Format	`flush`
Variable Name	`flush`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`OFF`

Variable Name	`hostname`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`string`

Variable Name	`large_files_support`
Variable Scope	Global
Dynamic Variable	No

Variable Name	`large_page_size`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type (linux)	`numeric`
	Default	`0`

Variable Name	`lc_time_names`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`string`

Variable Name	`license`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`string`
	Default	`GPL`

Variable Name	`local_infile`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`

Variable Name	`locked_in_memory`
Variable Scope	Global
Dynamic Variable	No

Variable Name	`log_bin`
Variable Scope	Global
Dynamic Variable	No

Command-Line Format	`--log-slow-admin-statements`
Option-File Format	`log-slow-admin-statements`
	Permitted Values
	Type	`boolean`
	Default	`FALSE`

Command-Line Format	`--log-slow-slave-statements`
Option-File Format	`log-slow-slave-statements`
	Permitted Values
	Type	`boolean`
	Default	`off`

Variable Name	`max_insert_delayed_threads`
Variable Scope	Global, Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`

Server System Variables

Table 5.2. System Variable Summary

Retornar

Version Introduced	5.6.4
Variable Name	`metadata_locks_cache_size`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`numeric`
	Default	`1024`
	Range	`1 .. 1048576`

Variable Name	`myisam_recover_options`
Variable Scope	Global
Dynamic Variable	No

Variable Name	`named_pipe`
Variable Scope	Global
Dynamic Variable	No
Platform Specific	windows
	Permitted Values
	Type (windows)	`boolean`
	Default	`OFF`

Command-Line Format	`--old`
Option-File Format	`old`
Variable Name	`old`
Variable Scope	Global
Dynamic Variable	No

Variable Name	`protocol_version`
Variable Scope	Global
Dynamic Variable	No
	Permitted Values
	Type	`numeric`

Variable Name	`proxy_user`
Variable Scope	Session
Dynamic Variable	No
	Permitted Values
	Type	`string`

Variable Name	`pseudo_thread_id`
Variable Scope	Session
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`

Variable Name	`rpl_semi_sync_master_enabled`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`boolean`
	Default	`OFF`

Variable Name	`rpl_semi_sync_master_timeout`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`10000`

Variable Name	`rpl_semi_sync_master_trace_level`
Variable Scope	Global
Dynamic Variable	Yes
	Permitted Values
	Type	`numeric`
	Default	`32`