Search Results
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 ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-indexes.html
If the table has a multiple-column index, any leftmost prefix of the index can be used by the optimizer to look up rows. This is optimized by a preprocessor that checks whether you are using WHERE key_part_N = constant on all key parts that occur ...
https://dev.mysql.com/doc/refman/8.4/en/outer-join-simplification.html
When the optimizer evaluates plans for outer join operations, it takes into consideration only plans where, for each such operation, the outer tables are accessed before the inner tables. The optimizer choices are limited because only such plans ...