EXPLAIN Syntax

Or:

EXPLAIN tbl_name

The EXPLAIN statement can be used either as a way to obtain information about how MariaDB executes a statement, or as a synonym for DESCRIBE:

• When you precede a statement with the keyword EXPLAIN, MariaDB displays information from the optimizer about the statement execution plan. That is, MariaDB explains how it would process the statement, including information about how tables are joined and in which order. EXPLAIN EXTENDED can be used to provide additional information.

  As of MariaDB 5.6.3, EXPLAIN provides information about SELECT, DELETE, INSERT, REPLACE, and UPDATE statements. Before MariaDB 5.6.3, EXPLAIN provides information only about SELECT statements.

  For information about using EXPLAIN and EXPLAIN EXTENDED to obtain query execution plan information, see , "Optimizing Queries with EXPLAIN".

• EXPLAIN PARTITIONS is useful only when examining queries involving partitioned tables. For details, see , "Obtaining Information About Partitions".
• As of MariaDB 5.6.5, the FORMAT option can be used to select the output format. TRADITIONAL presents the output in tabular format. This is the default if no FORMAT option is present. JSON format displays the information in JSON format. With FORMAT = JSON, the output includes extended and partition information.
• EXPLAIN tbl_name is synonymous with DESCRIBE tbl_name or SHOW COLUMNS FROM tbl_name. For information about DESCRIBE and SHOW COLUMNS, see , "DESCRIBE Syntax", and , "SHOW COLUMNS Syntax".

Retornar