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https://dev.mysql.com/doc/refman/8.4/en/optimizer-hints.html
One means of control over optimizer strategies is to set the optimizer_switch system variable (see Section 10.9.2, “Switchable Optimizations”). Changes to this variable affect execution of all subsequent queries; to affect one query differently ...*/ C-style comment syntax, with a + character following the /* comment opening ...
https://dev.mysql.com/doc/refman/8.4/en/switchable-optimizations.html
Its value is a set of flags, each of which has a value of on or off to indicate whether the corresponding optimizer behavior is enabled or disabled. To see the current set of optimizer flags, select the variable value: mysql> SELECT ...This variable ...
https://dev.mysql.com/doc/refman/8.4/en/optimize-table.html
OPTIMIZE TABLE reorganizes the physical storage of table data and associated index data, to reduce storage space and improve I/O efficiency when accessing the table. Use OPTIMIZE TABLE in these cases, depending on the type of table: After doing ...
https://dev.mysql.com/doc/refman/8.4/en/range-optimization.html
The following sections describe conditions under which the optimizer uses range access. The optimizer attempts to use additional key parts to determine the interval as long as the comparison operator is =, <=>, or IS NULL. If the operator is >, <, ... The range access method uses a single index to retrieve a subset of table rows that are contained within one or several index value ...
https://dev.mysql.com/doc/internals/en/optimizer-other-optimizations.html
In this section, we discuss other, more specialized optimizations performed in the MySQL server.
https://dev.mysql.com/doc/internals/en/optimizer-primary-optimizations.html
This section discusses the most important optimizations performed by the server.
https://dev.mysql.com/doc/refman/8.4/en/derived-table-optimization.html
The optimizer handles derived tables, view references, and common table expressions the same way: It avoids unnecessary materialization whenever possible, which enables pushing down conditions from the outer query to derived tables and produces more ...The outer query does not specify DISTINCT, HAVING, or ORDER ...
https://dev.mysql.com/doc/refman/8.4/en/order-by-optimization.html
This section describes when MySQL can use an index to satisfy an ORDER BY clause, the filesort operation used when an index cannot be used, and execution plan information available from the optimizer about ORDER BY. An ORDER BY with and without ...
https://dev.mysql.com/doc/refman/8.4/en/subquery-optimization-with-exists.html
Certain optimizations are applicable to comparisons that use the IN (or =ANY) operator to test subquery results. This section discusses these optimizations, particularly with regard to the challenges that NULL values present. The last part of the ...Consider the following subquery comparison: outer_expr IN (SELECT inner_expr FROM ...
https://dev.mysql.com/doc/mysql-em-plugin/en/myoem-config-metric-optimizer-category.html
Lists the Optimizer configuration metrics and provides a brief description of each. Table 7.24 Optimizer Configuration Metrics NameDescriptionEnd Markers In Json Enabled Whether optimizer JSON output adds end markers. Eq Range Index Dive Limit ...