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https://dev.mysql.com/doc/refman/5.7/en/explain-extended.html
The Message value in SHOW WARNINGS output displays how the optimizer qualifies table and column names in the SELECT statement, what the SELECT looks like after the application of rewriting and optimization rules, and possibly other notes about the ... For SELECT statements, the EXPLAIN statement produces extra (“extended”) information that is not part of EXPLAIN output but can be viewed by issuing a SHOW WARNINGS statement following ...
https://dev.mysql.com/doc/refman/5.7/en/function-resolution.html
When the parser encounters a word that is the name of a built-in function, it must determine whether the name signifies a function call or is instead a nonexpression reference to an identifier such as a table or column name. This occurs even when ...
https://dev.mysql.com/doc/refman/5.7/en/index-hints.html
They also work with multi-table DELETE statements, but not with single-table DELETE, as shown later in this section. (For the general syntax for specifying tables in a SELECT statement, see Section 13.2.9.2, “JOIN Clause”.) The syntax for ...
https://dev.mysql.com/doc/refman/5.7/en/innodb-online-ddl-space-requirements.html
Online DDL operations have the following space requirements: Temporary log files: A temporary log file records concurrent DML when an online DDL operation creates an index or alters a table. If the operation takes a long time and concurrent DML ...
https://dev.mysql.com/doc/refman/5.7/en/innodb-system-tablespace.html
The system tablespace is the storage area for the InnoDB data dictionary, the doublewrite buffer, the change buffer, and undo logs. It may also contain table and index data if tables are created in the system tablespace rather than file-per-table ...To do so, specify the autoextend attribute for the last data file in the innodb_data_file_path setting, and restart the ...
https://dev.mysql.com/doc/refman/5.7/en/innodb-undo-logs.html
Rollback segments reside in the system tablespace, in undo tablespaces, and in the temporary tablespace. Undo logs that reside in the temporary tablespace are used for transactions that modify data in user-defined temporary tables. InnoDB supports a ... An undo log is a collection of undo log records associated with a single read-write ...
https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-ndb-api-statistics.html
Such actions include starting and closing (or aborting) transactions; primary key and unique key operations; table, range, and pruned scans; threads blocked while waiting for the completion of various operations; and data and events sent and ... A ...
https://dev.mysql.com/doc/refman/5.7/en/performance-schema-restrictions.html
If you save event information in another table, you should not assume that the original events are still available later. For example, if you select events from a performance_schema table into a temporary table, intending to join that table with the ... The Performance Schema avoids using mutexes to collect or produce data, so there are no guarantees of consistency and results can sometimes be ...
https://dev.mysql.com/doc/refman/5.7/en/query-cache-operation.html
If a table changes, all cached queries that use the table become invalid and are removed from the cache. This includes queries that use MERGE tables that map to the changed table. A table can be changed by many types of statements, such as INSERT, ... Note The query cache is deprecated as of MySQL 5.7.20, and is removed in MySQL ...
https://dev.mysql.com/doc/refman/5.7/en/show-engine.html
Note InnoDB mutexes and rwlocks can also be monitored using Performance Schema tables. Interpret buffer names as follows: An internal buffer that is not exposed as a table is named within parentheses. An internal buffer that is exposed as a table in ... SHOW ENGINE engine_name {STATUS | MUTEX} SHOW ENGINE displays operational information about a storage ...