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https://dev.mysql.com/doc/internals/en/optimizer-order-by-clauses.html
In general, the optimizer will skip the sort procedure for the ORDER BY clause if it sees that the rows will be in order anyway. For the query: SELECT column1 FROM Table1 ORDER BY 'x'; the optimizer will throw out the ORDER BY clause. For the ...
https://dev.mysql.com/doc/internals/en/optimizer-index-merge-join-type.html
The Index Merge optimizer collects a list of possible ways to access rows with Index Merge. 7.2.2.5.3 The range Optimizer For range queries, the MySQL optimizer builds a SEL_TREE object which represents a condition in this form: range_cond = ...
https://dev.mysql.com/doc/refman/8.4/en/explain-output.html
For MyISAM tables, running ANALYZE TABLE helps the optimizer choose better indexes. Because there is only one row, values from the column in this row can be regarded as constants by the rest of the optimizer. This join type optimization is used most ... The EXPLAIN statement provides information about how MySQL executes ...
https://dev.mysql.com/doc/internals/en/optimizer-and-relations.html
An ANDed search has the form condition1 AND condition2, as in this example: WHERE column1 = 'x' AND column2 = 'y' Here, the optimizer's decision process can be described as follows: If (neither condition is indexed) use sequential scan. The ...
https://dev.mysql.com/doc/internals/en/optimizer-range-join-type.html
The optimizer will use an index (range search) for column1 LIKE 'x%' but not for column1 LIKE '%x' That is, there is no range search if the first character in the pattern is a wildcard. To the optimizer, column1 BETWEEN 5 AND 7 is the same as this ... Some conditions can work with indexes, but over a (possibly wide) range of ...
https://dev.mysql.com/doc/refman/8.4/en/disk-issues.html
For information about optimizing an InnoDB configuration to improve I/O performance, see Section 10.5.8, “Optimizing InnoDB Disk I/O”. You have to choose to optimize for random or sequential access. This section describes ways to configure ...
https://dev.mysql.com/doc/internals/en/optimizer-or-relations.html
An ORed search has the form condition1 OR condition2, as in this example: WHERE column1 = 'x' OR column2 = 'y' Here the optimizer's decision is to use a sequential scan. See Section 7.2.2.5.2, “Index Merge Optimizer” and Index Merge ...There is ...
https://dev.mysql.com/doc/internals/en/optimizer-partition-pruning.html
Therefore its implementation is a part of the MySQL Query Optimizer. The extraction process uses the Range Analyzer — a part of the MySQL optimizer that produces plans for the range access method. Note In certain cases the result of the RANGE ...
https://dev.mysql.com/doc/refman/8.4/en/hash-joins.html
It is possible to control whether hash joins are employed using one of the BNL and NO_BNL optimizer hints, or by setting block_nested_loop=on or block_nested_loop=off as part of the setting for the optimizer_switch server system variable. This means ...row *************************** id: 1 select_type: SIMPLE table: t1 partitions: NULL type: ALL possible_keys: NULL key: NULL key_len: NULL ref: NULL rows: 1 filtered: 100.00 Extra: NULL ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-optimizer-trace-table.html
The OPTIMIZER_TRACE table provides information produced by the optimizer tracing capability for traced statements. The OPTIMIZER_TRACE table has these columns: QUERY The text of the traced statement. MISSING_BYTES_BEYOND_MAX_MEM_SIZE Each ...If ...