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https://dev.mysql.com/doc/refman/8.0/en/performance-schema-optimization.html
row *************************** id: 1 select_type: SIMPLE table: accounts partitions: NULL type: const possible_keys: ACCOUNT key: ACCOUNT key_len: 278 ref: const,const rows: 1 filtered: 100.00 Extra: NULL The EXPLAIN output indicates that the ...
https://dev.mysql.com/doc/refman/8.0/en/show-warnings.html
SHOW WARNINGS is also used following EXPLAIN, to display the extended information generated by EXPLAIN. SHOW WARNINGS [LIMIT [offset,] row_count] SHOW COUNT(*) WARNINGS SHOW WARNINGS is a diagnostic statement that displays information about the ...
https://dev.mysql.com/doc/refman/8.0/en/using-spatial-indexes.html
| +-----+---------------------------------------------------------------+ 20 rows in set (0.00 sec) Use EXPLAIN to check the way this query is executed: mysql> SET @poly = -> 'Polygon((30000 15000, 31000 15000, 31000 16000, 30000 16000, 30000 ...
https://dev.mysql.com/doc/refman/8.0/en/bnl-bka-optimization.html
In EXPLAIN output, use of BNL for a table is signified when the Extra value contains Using join buffer (Block Nested Loop) and the type value is ALL, index, or range. In EXPLAIN output, use of BKA for a table is signified when the Extra value ... In ...
https://dev.mysql.com/doc/refman/8.0/en/column-indexes.html
An implication of this behavior is that EXPLAIN for full-text queries is typically slower than for non-full-text queries for which no expression evaluation occurs during the optimization phase. EXPLAIN for full-text queries may show Select tables ...
https://dev.mysql.com/doc/refman/8.0/en/describe.html
The DESCRIBE and EXPLAIN statements are synonyms, used either to obtain information about table structure or query execution plans. For more information, see Section 15.7.7.5, “SHOW COLUMNS Statement”, and Section 15.8.2, “EXPLAIN ...
https://dev.mysql.com/doc/refman/8.0/en/enum.html
and these potential issues to consider: If you make enumeration values that look like numbers, it is easy to mix up the literal values with their internal index numbers, as explained in Enumeration Limitations. Using ENUM columns in ORDER BY clauses ... An ENUM is a string object with a value chosen from a list of permitted values that are enumerated explicitly in the column specification at table creation ...
https://dev.mysql.com/doc/refman/8.0/en/execution-plan-information.html
The set of operations that the optimizer chooses to perform the most efficient query is called the “query execution plan”, also known as the EXPLAIN plan. Your goals are to recognize the aspects of the EXPLAIN plan that indicate a query is ...
https://dev.mysql.com/doc/refman/8.0/en/group-by-optimization.html
If the WHERE clause contains range predicates (see the discussion of the range join type in Section 10.8.1, “Optimizing Queries with EXPLAIN”), a Loose Index Scan looks up the first key of each group that satisfies the range conditions, and ...
https://dev.mysql.com/doc/refman/8.0/en/group-replication-connection-security.html
group_replication_recovery_use_ssl and the other group_replication_recovery_* system variables are explained in Section 20.6.3.2, “Secure Socket Layer (SSL) Connections for Distributed Recovery”. To restart the group, follow the process in ...