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https://dev.mysql.com/doc/refman/8.4/en/index-extensions.html
The optimizer takes into account the primary key columns of the extended secondary index when determining how and whether to use that index. The optimizer can use extended secondary indexes for ref, range, and index_merge index access, for Loose ...
https://dev.mysql.com/doc/refman/8.4/en/myisamchk-table-info.html
Possible values are crashed, open, changed, analyzed, optimized keys, and sorted index pages. For an optimized table without fragmented rows, this is the same as Data records. To obtain a description of a MyISAM table or statistics about it, use ...
https://dev.mysql.com/doc/mysql-monitor/8.0/en/memory-usage-advisors-ref.html
Default frequency 00:05:00 Default auto-close enabled no Key Buffer Size May Not Be Optimal For Key Cache The key cache hit ratio represents the proportion of keys that are being read from the key cache in memory instead of from disk. Default ...It ...
https://dev.mysql.com/doc/refman/8.4/en/index-hints.html
Index hints give the optimizer information about how to choose indexes during query processing. Index hints, described here, differ from optimizer hints, described in Section 10.9.3, “Optimizer Hints”. Note MySQL 8.4 supports the index-level ...
https://dev.mysql.com/doc/refman/8.4/en/mysqlcheck.html
The mysqlcheck client performs table maintenance: It checks, repairs, optimizes, or analyzes tables. mysqlcheck uses the SQL statements CHECK TABLE, REPAIR TABLE, ANALYZE TABLE, and OPTIMIZE TABLE in a convenient way for the user. Command Meaning ...Each table is locked and therefore unavailable to other sessions while it is being processed, although for check operations, the table is locked with a READ lock only (see Section 15.3.6, “LOCK TABLES and UNLOCK TABLES Statements”, for more information about READ and WRITE ...
https://dev.mysql.com/doc/heatwave/en/mys-hw-autopilot.html
HeatWave Autopilot makes the HeatWave query optimizer increasingly intelligent as more queries are executed, resulting in continually improving system performance. Data Load Auto Parallel Load Optimizes load time and memory usage by predicting the ... HeatWave Autopilot automates many of the most important and often challenging aspects of achieving exceptional query performance at scale, including cluster provisioning, loading data, query processing, and failure ...
https://dev.mysql.com/doc/heatwave/en/mys-hw-running-queries-best-practice.html
The following practices are recommended when running queries: If a query fails to offload and you cannot identify the reason, enable tracing and query the INFORMATION_SCHEMA.OPTIMIZER_TRACE table to debug the query. If the optimizer trace does not ...For example, the following query contains a subquery and is not offloaded as indicated by the EXPLAIN output, which does not show “Using secondary ...
https://dev.mysql.com/doc/refman/8.4/en/explain-extended.html
The Message value in SHOW WARNINGS output displays how the optimizer qualifies table and column names in the SELECT statement, what the SELECT looks like after the application of rewriting and optimization rules, and possibly other notes about the ... The EXPLAIN statement produces extra (“extended”) information that is not part of EXPLAIN output but can be viewed by issuing a SHOW WARNINGS statement following ...
https://dev.mysql.com/doc/refman/8.4/en/join.html
Index hints can be specified to affect how the MySQL optimizer makes use of indexes. Optimizer hints and the optimizer_switch system variable are other ways to influence optimizer use of indexes. This includes a join handled by merging derived ...
https://dev.mysql.com/doc/refman/8.4/en/system-schema.html
Data Dictionary Tables Grant System Tables Object Information System Tables Log System Tables Server-Side Help System Tables Time Zone System Tables Replication System Tables Optimizer System Tables Miscellaneous System Tables The remainder of this ...It contains tables that store information required by the MySQL server as it ...