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https://dev.mysql.com/doc/refman/8.4/en/optimize-overview.html
Typical users aim to get the best database performance out of their existing software and hardware configurations. Advanced users look for opportunities to improve the MySQL software itself, or develop their own storage engines and hardware ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-consumer-configurations.html
The consumer settings in the setup_consumers table form a hierarchy from higher levels to lower. The following discussion describes how consumers work, showing specific configurations and their effects as consumer settings are enabled progressively ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-persisted-variables-table.html
The persisted_variables table provides an SQL interface to the mysqld-auto.cnf file that stores persisted global system variable settings, enabling the file contents to be inspected at runtime using SELECT statements. Variables are persisted using ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-queries.html
Pre-filtering limits which event information is collected and is independent of any particular user. By contrast, post-filtering is performed by individual users through the use of queries with appropriate WHERE clauses that restrict what event ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-setup-objects-table.html
Rows can be inserted into or deleted from setup_objects by users with the INSERT or DELETE privilege on the table. For existing rows, only the ENABLED and TIMED columns can be modified, by users with the UPDATE privilege on the table. The ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-table-characteristics.html
The name of the performance_schema database is lowercase, as are the names of tables within it. Many tables in the performance_schema database are read only and cannot be modified: mysql> TRUNCATE TABLE performance_schema.setup_instruments; ERROR ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-table-wait-summary-tables.html
In this way, aggregations at higher levels are available directly without the need for user-defined views that sum lower-level columns. In this way, aggregations at higher levels are available directly without the need for user-defined views that ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-timing.html
Cycle counters also have disadvantages: End users expect to see timings in wall-clock units, such as fractions of a second. For example, on Pentiums, the instruction is RDTSC (an assembly-language rather than a C instruction) and it is theoretically ... Events are collected by means of instrumentation added to the server source ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-tp-connections-table.html
CONNECT_HANDLER_INDEX The index of the connection handler thread in the group which processed the connection request; a higher number means the connection load has triggered the creation of additional connection handler threads. TYPE The connection ... The tp_connections table contains one row per connection managed by the Thread Pool ...
https://dev.mysql.com/doc/refman/8.4/en/preventing-use-of-optimizer-trace.html
If, for some reason, you wish to prevent users from seeing traces of their queries, start the server with the options shown here: --maximum-optimizer-trace-max-mem-size=0 --optimizer-trace-max-mem-size=0 This sets the maximum size to 0 and prevents ...