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https://dev.mysql.com/doc/mysql-monitor/8.0/en/mem-features-qrti.html
Reading QRTi Values The queries listed on the Query Analyzer page also have a color-coded pie chart representing a breakdown of the values used in the QRTi calculation; green representing the optimal percentage, yellow the acceptable percentage, and ...It is a "quality of service" measurement for each query, and uses the Apdex formula for that calculation: Apdex on ...
https://dev.mysql.com/doc/heatwave/en/mys-hw-debugging-queries.html
Query debugging is performed by enabling MySQL optimizer trace and querying the INFORMATION_SCHEMA.OPTIMIZER_TRACE table for the failure reason. To enable MySQL optimizer trace, set the optimizer_trace and optimizer_trace_offset variables as shown: ... This section describes how to debug queries that fail to offload to HeatWave for ...
https://dev.mysql.com/doc/refman/8.4/en/alter-table-partition-operations.html
These include ANALYZE PARTITION, CHECK PARTITION, OPTIMIZE PARTITION, REBUILD PARTITION, and REPAIR PARTITION. OPTIMIZE PARTITION causes the entire table to rebuilt and analyzed, and an appropriate warning to be issued. The ANALYZE PARTITION, CHECK ... Partitioning-related clauses for ALTER TABLE can be used with partitioned tables for repartitioning, to add, drop, discard, import, merge, and split partitions, and to perform partitioning ...
https://dev.mysql.com/doc/refman/8.4/en/archive-storage-engine.html
You can use OPTIMIZE TABLE to analyze the table and pack it into a smaller format (for a reason to use OPTIMIZE TABLE, see later in this section). To achieve better compression, you can use OPTIMIZE TABLE or REPAIR TABLE. See Section 15.7.3.4, ...
https://dev.mysql.com/doc/refman/8.4/en/derived-tables.html
The optimizer determines information about derived tables in such a way that EXPLAIN does not need to materialize them. See Section 10.2.2.4, “Optimizing Derived Tables, View References, and Common Table Expressions with Merging or ...For ...
https://dev.mysql.com/doc/refman/8.4/en/index-btree-hash.html
Any index that does not span all AND levels in the WHERE clause is not used to optimize the query. WHERE index=1 OR A=10 AND index=2 /* optimized like "index_part1='hello'" */ ... One circumstance under which this occurs is when the optimizer ...
https://dev.mysql.com/doc/refman/8.4/en/information-functions.html
The former involves the parser, optimizer, table locking, and runtime evaluation N times each. Memory structures already allocated are reused, and runtime optimizations such as local caching of results already evaluated for aggregate functions can ...It may be used to time how quickly MySQL processes the ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-ft-being-deleted-table.html
The INNODB_FT_BEING_DELETED table provides a snapshot of the INNODB_FT_DELETED table; it is used only during an OPTIMIZE TABLE maintenance operation. When OPTIMIZE TABLE is run, the INNODB_FT_BEING_DELETED table is emptied, and DOC_ID values are ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-page-compression.html
Writes to the tablespace that occur after setting the new compression algorithm use the new setting, but to apply the new compression algorithm to existing pages, you must rebuild the table using OPTIMIZE TABLE. ALTER TABLE t1 COMPRESSION="zlib"; ...
https://dev.mysql.com/doc/refman/8.4/en/known-issues.html
The following problems are known: Subquery optimization for IN is not as effective as for =. SELECT with no ORDER BY, the SELECT may return rows in a different order (which results in a row having different ranks, hence getting a different number in ... This section lists known issues in recent versions of ...