![]() ![]() | 2 | DEPENDENT SUBQUERY | h2 | ALL | NULL | NULL | NULL | NULL | 6 | 100. | 1 | PRIMARY | h1 | ALL | NULL | NULL | NULL | NULL | 6 | 100.00 | Using where | | id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra | Will produce something like this on PostgreSQL, QUERY PLAN įor instance this is taken from this example, EXPLAIN ANALYZE SELECT * ![]() For information about DESCRIBE and SHOW COLUMNS, see O EXPLAIN tbl_name is synonymous with DESCRIBE tbl_name or SHOW COLUMNSįROM tbl_name. O EXPLAIN PARTITIONS is useful only when examining queries involving Including information about how tables are joined and in which order.ĮXPLAIN EXTENDED can be used to obtain additional information.įor information about using EXPLAIN and EXPLAIN EXTENDED to obtain That is, MySQL explains how it would process the statement, O When you precede a SELECT statement with the keyword EXPLAIN, MySQLĭisplays information from the optimizer about the query execution The EXPLAIN statement can be used either as a way to obtain informationĪbout how MySQL executes a statement, or as a synonym for DESCRIBE: Name: 'EXPLAIN'ĮXPLAIN SELECT select_options EXPLAIN EXTENDED provides no timing information whatsoever, and the internal break down is far less verbose. However there is no substitute for EXPLAIN ANALYZE. You might find that it takes a while to get used to the way that it does certain things. However, there are syntactical differences that are very important. MariaDB/MySQL provide something called EXPLAIN EXTENDED. Of course - if you know SQL and relational databases well you can manage any database. ![]()
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