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https://dev.mysql.com/doc/refman/8.0/en/controlling-optimizer.html
The server maintains histogram statistics about column values in the column_statistics data dictionary table (see Section 10.9.6, “Optimizer Statistics”). Like other data dictionary tables, this table is not directly accessible by users. MySQL ...
https://dev.mysql.com/doc/refman/8.0/en/controlling-query-plan-evaluation.html
For join queries, the number of possible plans investigated by the MySQL optimizer grows exponentially with the number of tables referenced in a query. For small numbers of tables (typically less than 7 to 10) this is not a problem. The behavior of ... The task of the query optimizer is to find an optimal plan for executing an SQL ...
https://dev.mysql.com/doc/refman/8.0/en/data-dictionary-object-cache.html
The tablespace_definition_cache option sets a limit for the number of tablespace definition objects that can be stored in the dictionary object cache. The table definition cache partition exists in parallel with the table definition cache that is ...
https://dev.mysql.com/doc/refman/8.0/en/delete-optimization.html
The time required to delete individual rows in a MyISAM table is exactly proportional to the number of indexes. To delete all rows from a MyISAM table, TRUNCATE TABLE tbl_name is faster than DELETE FROM tbl_name. Truncate operations are not ...To ...
https://dev.mysql.com/doc/refman/8.0/en/estimating-performance.html
For small tables, you can usually find a row in one disk seek (because the index is probably cached). For bigger tables, you can estimate that, using B-tree indexes, you need this many seeks to find a row: log(row_count) / log(index_block_length / 3 ... In most cases, you can estimate query performance by counting disk ...
https://dev.mysql.com/doc/refman/8.0/en/faqs-general.html
For the syntax required to perform multiple-table updates, see Section 15.2.17, “UPDATE Statement”; for that required to perform multiple-table deletes, see Section 15.2.2, “DELETE Statement”. A multiple-table insert can be accomplished ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-memcached-intro.html
Direct access to InnoDB tables, bypassing the SQL parser, the optimizer, and even the Handler API layer. Although memcached has no concept of transactions, you can use this option to control how soon memcached sees changes caused by SQL statements ... The InnoDB memcached plugin implements memcached as a MySQL plugin daemon that accesses the InnoDB storage engine directly, bypassing the MySQL SQL ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-performance-midpoint_insertion.html
The goal is to make sure that frequently accessed (“hot”) pages remain in the buffer pool, even as read-ahead and full table scans bring in new blocks that might or might not be accessed afterward. You can control the insertion point in the LRU ... Rather than using a strict LRU algorithm, InnoDB uses a technique to minimize the amount of data that is brought into the buffer pool and never accessed ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-troubleshooting.html
If the problem is with table creation, tablespaces, or data dictionary operations, refer to the InnoDB Information Schema system tables to examine contents of the InnoDB internal data dictionary. The following general guidelines apply to ...
https://dev.mysql.com/doc/refman/8.0/en/install-component.html
INSTALL COMPONENT requires the INSERT privilege for the mysql.component system table because it adds a row to that table to register the component. Specifying PERSIST for any variable in SET silently executes SET PERSIST_ONLY immediately after ...