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https://dev.mysql.com/doc/refman/8.4/en/optimizer-issues.html
MySQL uses a cost-based optimizer to determine the best way to resolve a query. In many cases, MySQL can calculate the best possible query plan, but sometimes MySQL does not have enough information about the data at hand and has to make ...To use ...Use ANALYZE TABLE tbl_name to update the key distributions for the scanned ...
https://dev.mysql.com/doc/refman/8.4/en/optimizing-innodb-queries.html
To tune queries for InnoDB tables, create an appropriate set of indexes on each table. Follow these guidelines for InnoDB indexes: Because each InnoDB table has a primary key (whether you request one or not), specify a set of primary key columns ...
https://dev.mysql.com/doc/refman/8.4/en/thread-pool-elements.html
For example, if an application uses this query: SELECT * FROM INFORMATION_SCHEMA.TP_THREAD_STATE; The application should use this query instead: SELECT * FROM performance_schema.tp_thread_state; Note If you do not load all the monitoring tables, ...
https://dev.mysql.com/doc/refman/8.4/en/keyring-file-component.html
If an error occurs, server startup fails and the administrator must correct any issues indicated by diagnostics in the server error log. The component_keyring_file keyring component stores keyring data in a file local to the server host. To use ...
https://dev.mysql.com/doc/refman/8.4/en/diagnostics-area.html
RETURNED_SQLSTATE: A string that indicates the SQLSTATE value for the condition. MYSQL_ERRNO: An integer that indicates the MySQL error code for the condition. For the RETURNED_SQLSTATE, MESSAGE_TEXT, and MYSQL_ERRNO values for particular errors, ...
https://dev.mysql.com/doc/refman/8.4/en/error-log-rule-based-filtering.html
The following example enables log_filter_dragnet in combination with the built-in log sink: INSTALL COMPONENT 'file://component_log_filter_dragnet'; SET GLOBAL log_error_services = 'log_filter_dragnet; log_sink_internal'; To set log_error_services ... The log_filter_dragnet log filter component enables log filtering based on user-defined ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-events-table.html
REPLICA_SIDE_DISABLED indicates that the creation of the event occurred on another MySQL server acting as a replication source and replicated to the current MySQL server which is acting as a replica, but the event is not presently being executed on ...ORIGINATOR The server ID of the MySQL server on which the event was created; used in ...EVENT_DEFINITION The text of the SQL ... The ...
https://dev.mysql.com/doc/refman/8.4/en/show-processlist.html
The MySQL process list indicates the operations currently being performed by the set of threads executing within the server. A value of system user refers to a nonclient thread spawned by the server to handle tasks internally, for example, a ...It ...
https://dev.mysql.com/doc/refman/8.4/en/version-tokens.html
MySQL includes Version Tokens, a feature that enables creation of and synchronization around server tokens that applications can use to prevent accessing incorrect or out-of-date data. In addition, an application that communicates with a server can ...An application can use token locks to indicate to other cooperating applications that tokens are in use and should not be ...The Version Tokens ...
https://dev.mysql.com/doc/mysql-secure-deployment-guide/8.0/en/secure-deployment-install.html
Data directory initialization and subsequent server startup steps fail if this library is not installed locally. It is also used to run the mysqld server process, as defined in the systemd mysqld.service file (see Starting the Server using systemd).