The table_lock_waits_summary_by_table Table

The table_lock_waits_summary_by_table table aggregates all table lock wait events, as generated by the wait/lock/table/sql/handler instrument. The grouping is by table.

TRUNCATE TABLE is permitted for summary tables. It resets the counters to zero rather than removing rows.

This table contains information about internal and external locks:

• An internal lock corresponds to a lock in the SQL layer. This is currently implemented by a call to thr_lock(). In event rows, these locks are distinguished by the OPERATION column, which will have one of these values:

  read normal read with shared locks read high priority read no insert write allow write write concurrent insert write delayed write low priority write normal
  

• An external lock corresponds to a lock in the storage engine layer. This is currently implemented by a call to handler::external_lock(). In event rows, these locks are distinguished by the OPERATION column, which will have one of these values:

  read external write external
  

The table_lock_waits_summary_by_table table has these grouping columns to indicate how events are aggregated: OBJECT_TYPE, OBJECT_SCHEMA, and OBJECT_NAME. These columns have the same meaning as in the events_waits_current table. They identify the table to which the row applies.

table_lock_waits_summary_by_table has the following summary columns containing aggregated values. As indicated in the column descriptions, some columns are more general and have values that are the same as the sum of the values of more fine-grained columns. For example, columns that aggregate all writes hold the sum of the corresponding columns that aggregate inserts, updates, and deletes. In this way, aggregations at higher levels are available directly without the need for user-defined views that sum lower-level columns.

• COUNT_STAR, SUM_TIMER_WAIT, MIN_TIMER_WAIT, AVG_TIMER_WAIT, MAX_TIMER_WAIT

  These columns aggregate all lock operations. They are the same as the sum of the corresponding xxx_READ and xxx_WRITE columns.

• COUNT_READ, SUM_TIMER_READ, MIN_TIMER_READ, AVG_TIMER_READ, MAX_TIMER_READ

  These columns aggregate all read-lock operations. They are the same as the sum of the corresponding xxx_READ_NORMAL, xxx_READ_WITH_SHARED_LOCKS, xxx_READ_HIGH_PRIORITY, and xxx_READ_NO_INSERT columns.

• COUNT_WRITE, SUM_TIMER_WRITE, MIN_TIMER_WRITE, AVG_TIMER_WRITE, MAX_TIMER_WRITE

  These columns aggregate all write-lock operations. They are the same as the sum of the corresponding xxx_WRITE_ALLOW_WRITE, xxx_WRITE_CONCURRENT_INSERT, xxx_WRITE_DELAYED, xxx_WRITE_LOW_PRIORITY, and xxx_WRITE_NORMAL columns.

• COUNT_READ_NORMAL, SUM_TIMER_READ_NORMAL, MIN_TIMER_READ_NORMAL, AVG_TIMER_READ_NORMAL, MAX_TIMER_READ_NORMAL

  These columns aggregate internal read locks.

• COUNT_READ_WITH_SHARED_LOCKS, SUM_TIMER_READ_WITH_SHARED_LOCKS, MIN_TIMER_READ_WITH_SHARED_LOCKS, AVG_TIMER_READ_WITH_SHARED_LOCKS, MAX_TIMER_READ_WITH_SHARED_LOCKS

  These columns aggregate internal read locks.

• COUNT_READ_HIGH_PRIORITY, SUM_TIMER_READ_HIGH_PRIORITY, MIN_TIMER_READ_HIGH_PRIORITY, AVG_TIMER_READ_HIGH_PRIORITY, MAX_TIMER_READ_HIGH_PRIORITY

  These columns aggregate internal read locks.

• COUNT_READ_NO_INSERT, SUM_TIMER_READ_NO_INSERT, MIN_TIMER_READ_NO_INSERT, AVG_TIMER_READ_NO_INSERT, MAX_TIMER_READ_NO_INSERT

  These columns aggregate internal read locks.

• COUNT_READ_EXTERNAL, SUM_TIMER_READ_EXTERNAL, MIN_TIMER_READ_EXTERNAL, AVG_TIMER_READ_EXTERNAL, MAX_TIMER_READ_EXTERNAL

  These columns aggregate external read locks.

• COUNT_WRITE_ALLOW_WRITE, SUM_TIMER_WRITE_ALLOW_WRITE, MIN_TIMER_WRITE_ALLOW_WRITE, AVG_TIMER_WRITE_ALLOW_WRITE, MAX_TIMER_WRITE_ALLOW_WRITE

  These columns aggregate internal write locks.

• COUNT_WRITE_CONCURRENT_INSERT, SUM_TIMER_WRITE_CONCURRENT_INSERT, MIN_TIMER_WRITE_CONCURRENT_INSERT, AVG_TIMER_WRITE_CONCURRENT_INSERT, MAX_TIMER_WRITE_CONCURRENT_INSERT

  These columns aggregate internal write locks.

• COUNT_WRITE_DELAYED, SUM_TIMER_WRITE_DELAYED, MIN_TIMER_WRITE_DELAYED, AVG_TIMER_WRITE_DELAYED, MAX_TIMER_WRITE_DELAYED

  These columns aggregate internal write locks.

• COUNT_WRITE_LOW_PRIORITY, SUM_TIMER_WRITE_LOW_PRIORITY, MIN_TIMER_WRITE_LOW_PRIORITY, AVG_TIMER_WRITE_LOW_PRIORITY, MAX_TIMER_WRITE_LOW_PRIORITY

  These columns aggregate internal write locks.

• COUNT_WRITE_NORMAL, SUM_TIMER_WRITE_NORMAL, MIN_TIMER_WRITE_NORMAL, AVG_TIMER_WRITE_NORMAL, MAX_TIMER_WRITE_NORMAL

  These columns aggregate internal write locks.

• COUNT_WRITE_EXTERNAL, SUM_TIMER_WRITE_EXTERNAL, MIN_TIMER_WRITE_EXTERNAL, AVG_TIMER_WRITE_EXTERNAL, MAX_TIMER_WRITE_EXTERNAL

  These columns aggregate external write locks.

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