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https://dev.mysql.com/doc/refman/9.7/en/subquery-materialization.html
For subquery materialization to be used in MySQL, the optimizer_switch system variable materialization flag must be enabled. The optimizer uses materialization to enable more efficient subquery processing. Materialization speeds up query execution ...
https://dev.mysql.com/doc/refman/9.7/en/subquery-optimization-with-exists.html
WHERE inner_expr=outer_expr) The subquery_materialization_cost_based flag of the optimizer_switch system variable enables control over the choice between subquery materialization and IN-to-EXISTS subquery transformation. Certain optimizations are ...
https://dev.mysql.com/doc/refman/9.7/en/sys-list-add.html
This function and list_drop() can be useful for manipulating the value of system variables such as sql_mode and optimizer_switch that take a comma-separated list of values. Adds a value to a comma-separated list of values and returns the result.
https://dev.mysql.com/doc/refman/9.7/en/update.html
UPDATE is a DML statement that modifies rows in a table. An UPDATE statement can start with a WITH clause to define common table expressions accessible within the UPDATE. Single-table syntax: UPDATE [LOW_PRIORITY] [IGNORE] table_reference SET ...
https://dev.mysql.com/doc/refman/9.7/en/using-date.html
To have MySQL check all dates and accept only legal dates (unless overridden by IGNORE), set the sql_mode system variable to "NO_ZERO_IN_DATE,NO_ZERO_DATE". You should use this format in UPDATE expressions and in the WHERE clause of SELECT ...
https://dev.mysql.com/doc/refman/9.7/en/view-algorithms.html
If no ALGORITHM clause is present, the default algorithm is determined by the value of the derived_merge flag of the optimizer_switch system variable. The optional ALGORITHM clause for CREATE VIEW or ALTER VIEW is a MySQL extension to standard SQL.
https://dev.mysql.com/doc/refman/9.7/en/window-function-optimization.html
Window function evaluation may be affected by the value of the windowing_use_high_precision system variable, which determines whether to compute window operations without loss of precision. Window functions affect the strategies the optimizer ...
https://dev.mysql.com/doc/refman/9.7/en/window-function-restrictions.html
You should also be aware that queries using very large numbers of windows may require increasing the default thread stack size (thread_stack system variable). The SQL standard imposes a constraint on window functions that they cannot be used in ...
https://dev.mysql.com/doc/mysql-shell/9.7/en/configuring-router-user.html
To add a new MySQL Router account named myRouter1 to the InnoDB Cluster referenced by the variable testCluster, issue: mysqlsh> testCluster.setupRouterAccount('myRouter1') In this case, no domain is specified and so the account is created with the ... When MySQL Router connects to a Cluster, ClusterSet, or ReplicaSet, it requires a user account that has the correct ...
https://dev.mysql.com/doc/c-api/9.7/en/mysql-fetch-field-direct.html
For metadata-optional connections, this function returns NULL when the resultset_metadata system variable is set to NONE. MYSQL_FIELD * mysql_fetch_field_direct(MYSQL_RES *result, unsigned int fieldnr) Description Given a field number fieldnr for a ...