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https://dev.mysql.com/doc/refman/8.4/en/optimize-overview.html
Database performance depends on several factors at the database level, such as tables, queries, and configuration settings. These software constructs result in CPU and I/O operations at the hardware level, which you must minimize and make as ...
https://dev.mysql.com/doc/refman/8.4/en/partitioning-management-range-list.html
You also cannot use this statement to change the partitioning expression or column. Adding and dropping of range and list partitions are handled in a similar fashion, so we discuss the management of both sorts of partitioning in this section. For ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-functions.html
The thread ID return value is a value of the type given in the THREAD_ID column of Performance Schema tables. The connection ID argument is a value of the type given in the PROCESSLIST_ID column of the Performance Schema threads table or the Id ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-obtaining-parent-events.html
Rows of this table have a THREAD_ID column indicating the thread ID of the session that owns the lock, and an EVENT_ID column indicating the Performance Schema event that caused the lock. The relation is based on a nested set data model, so the join ...
https://dev.mysql.com/doc/refman/8.4/en/selecting-all.html
There is an exception to the principle that SELECT * selects all columns. If a table contains invisible columns, * does not include them. For example, you may happen to think that the birth date for Bowser doesn't seem quite right. Consulting your ...
https://dev.mysql.com/doc/refman/8.4/en/table-scan-avoidance.html
The output from EXPLAIN shows ALL in the type column when MySQL uses a full table scan to resolve a query. There are no usable restrictions in the ON or WHERE clause for indexed columns. You are comparing indexed columns with constant values and ...
https://dev.mysql.com/doc/refman/8.4/en/window-functions-usage.html
Standard SQL requires PARTITION BY to be followed by column names only. A MySQL extension is to permit expressions, not just column names. For example, if a table contains a TIMESTAMP column named ts, standard SQL permits PARTITION BY ts but not ...
https://dev.mysql.com/doc/mysql-enterprise-backup/8.4/en/backup-performance.html
(The copying and scanning mechanisms used by mysqlbackup do not rely on indexes to do their work.) For example, it is typically not helpful to create an index on each column of a table, because only one index is used by any query. Because the ...
https://dev.mysql.com/doc/mysql-cluster-manager/8.4/en/mcm-reset.html
The SendBufferMemory setting that applies to this connection is specified on the instance level, as you can see because the Level column value corresponding to this connection is empty; this means that it is possible to reset this value on the ...
https://dev.mysql.com/doc/mysql-errors/8.4/en/client-error-reference.html
You must reset the statement, rebind the result set columns, and execute the statement again Error number: 2058; Symbol: CR_ALREADY_CONNECTED; Message: This handle is already connected. Client error messages originate from within the MySQL client ...