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https://dev.mysql.com/doc/refman/8.4/en/show-triggers.html
SHOW TRIGGERS [{FROM | IN} db_name] [LIKE 'pattern' | WHERE expr] SHOW TRIGGERS lists the triggers currently defined for tables in a database (the default database unless a FROM clause is given). This statement returns results only for databases ...
https://dev.mysql.com/doc/refman/8.4/en/subqueries.html
For information about how the optimizer handles subqueries, see Section 10.2.2, “Optimizing Subqueries, Derived Tables, View References, and Common Table Expressions”. All subquery forms and operations that the SQL standard requires are ...
https://dev.mysql.com/doc/refman/8.4/en/subquery-materialization.html
Materialization speeds up query execution by generating a subquery result as a temporary table, normally in memory. The first time MySQL needs the subquery result, it materializes that result into a temporary table. Any subsequent time the result is ... The optimizer uses materialization to enable more efficient subquery ...
https://dev.mysql.com/doc/refman/8.4/en/subquery-optimization-with-exists.html
row *************************** id: 2 select_type: DEPENDENT SUBQUERY table: t2 type: ref_or_null possible_keys: maybe_null_key key: maybe_null_key key_len: 5 ref: func rows: 2 Extra: Using where; Using index ... Triggered equalities can be used by ... Certain optimizations are applicable to comparisons that use the IN (or =ANY) operator to test subquery ...
https://dev.mysql.com/doc/refman/8.4/en/sys-metrics.html
The metric type determines the source from which the name is taken: For global status variables: The VARIABLE_NAME column of the global_status table For InnoDB metrics: The NAME column of the INNODB_METRICS table For other metrics: A view-provided ... This view summarizes MySQL server metrics to show variable names, values, types, and whether they are ...
https://dev.mysql.com/doc/refman/8.4/en/sys-sys-get-config.html
Given a configuration option name, returns the option value from the sys_config table, or the provided default value (which may be NULL) if the option does not exist in the table. If so, the routine uses the variable value without reading the ...If ...
https://dev.mysql.com/doc/refman/8.4/en/triggers.html
A trigger is a named database object that is associated with a table, and that activates when a particular event occurs for the table. Some uses for triggers are to perform checks of values to be inserted into a table or to perform calculations on ...For example, rows can be inserted by INSERT or LOAD DATA statements, and an insert trigger activates for each inserted ...
https://dev.mysql.com/doc/refman/8.4/en/user-names.html
MySQL stores accounts in the user table of the mysql system database. For information about account representation in the user table, see Section 8.2.3, “Grant Tables”. Warning The MySQL user name length limit is hardcoded in MySQL servers and ...An account is defined in terms of a user name and the client host or hosts from which the user can connect to the ...
https://dev.mysql.com/doc/extending-mysql/8.4/en/writing-audit-plugins.html
Additionally, several places in the server call the audit interface when an auditable event occurs, so that registered audit plugins can be notified about the event if necessary. When the plugin is enabled, these variables can be inspected using ...
https://dev.mysql.com/doc/relnotes/mysql-cluster/8.4/en/news-8-4-4.html
(Bug #36951132) NDB Disk Data: mysqld did not use a disk scan for NDB tables with 256 disk columns or more. Such retry logic is not performed for transactions containing row events where the STMT_END_F flag is missing; instead, the statement is ...