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https://dev.mysql.com/doc/refman/8.4/en/nested-join-optimization.html
The following discussion refers to the join syntax described in Section 15.2.13.2, “JOIN Clause”. The syntax of table_factor is extended in comparison with the SQL Standard. The latter accepts only table_reference, not a list of them inside a ...
https://dev.mysql.com/doc/refman/8.4/en/operator-precedence.html
Operator precedences are shown in the following list, from highest precedence to the lowest. Operators that are shown together on a line have the same precedence. When used as a comparison operator, it has the same precedence as <=>, >=, >, <=, <, ...
https://dev.mysql.com/doc/refman/8.4/en/optimize-character.html
The GROUP BY and ORDER BY clauses can generate temporary tables, and these temporary tables can use the MEMORY storage engine if the original table does not contain any BLOB columns. For character and string columns, follow these guidelines: Use ...
https://dev.mysql.com/doc/refman/8.4/en/partitioning-limitations-storage-engines.html
The maximum number of partitions that can be defined for an NDB table depends on the number of data nodes and node groups in the cluster, the version of the NDB Cluster software in use, and other factors. In MySQL 8.4, partitioning support is not ...
https://dev.mysql.com/doc/refman/8.4/en/partitioning-overview.html
See the documentation for the DataMemory data node configuration parameter, as well as Section 25.2.2, “NDB Cluster Nodes, Node Groups, Fragment Replicas, and Partitions”, for more information. This section provides a conceptual overview of ...
https://dev.mysql.com/doc/refman/8.4/en/partitioning-range.html
For example, when executing a query such as EXPLAIN SELECT COUNT(*) FROM employees WHERE separated BETWEEN '2000-01-01' AND '2000-12-31' GROUP BY store_id;, MySQL can quickly determine that only partition p2 needs to be scanned because the remaining ... A table that is partitioned by range is partitioned in such a way that each partition contains rows for which the partitioning expression value lies within a given ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-error-summary-tables.html
row *************************** ERROR_NUMBER: 1317 ERROR_NAME: ER_QUERY_INTERRUPTED SQL_STATE: 70100 SUM_ERROR_RAISED: 1 SUM_ERROR_HANDLED: 0 FIRST_SEEN: 2016-06-28 11:01:49 LAST_SEEN: 2016-06-28 11:01:49 Each error summary table has one or more ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-events-waits-current-table.html
For example, it can be used with GROUP BY OBJECT_INSTANCE_BEGIN to see whether the load on 1,000 mutexes (that protect, say, 1,000 pages or blocks of data) is spread evenly or just hitting a few bottlenecks. The table stores one row per thread ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-file-summary-tables.html
Each file I/O summary table has one or more grouping columns to indicate how the table aggregates events. The Performance Schema maintains file I/O summary tables that aggregate information about I/O operations. Example file I/O event summary ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-memory-summary-tables.html
row *************************** EVENT_NAME: memory/sql/TABLE COUNT_ALLOC: 1381 COUNT_FREE: 924 SUM_NUMBER_OF_BYTES_ALLOC: 2059873 SUM_NUMBER_OF_BYTES_FREE: 1407432 LOW_COUNT_USED: 0 CURRENT_COUNT_USED: 457 HIGH_COUNT_USED: 461 ...Operation counts ...