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https://dev.mysql.com/doc/refman/8.0/en/switchable-optimizations.html
Its value is a set of flags, each of which has a value of on or off to indicate whether the corresponding optimizer behavior is enabled or disabled. This variable has global and session values and can be changed at runtime. To see the current set of ...
https://dev.mysql.com/doc/refman/8.0/en/create-index.html
CREATE [UNIQUE | FULLTEXT | SPATIAL] INDEX index_name [index_type] ON tbl_name (key_part,...) [index_option] [algorithm_option | lock_option] ... This guideline is especially important for InnoDB tables, where the primary key determines the ...
https://dev.mysql.com/doc/refman/8.0/en/group-replication.html
This chapter explains MySQL Group Replication and how to install, configure and monitor groups. Section 20.2, “Getting Started” explains how to configure multiple MySQL Server instances to create a group. Section 20.3, “Requirements and ...
https://dev.mysql.com/doc/refman/8.0/en/derived-tables.html
Before 8.0.14, it produces an error: Unknown column 't1.b' in 'where clause' The optimizer determines information about derived tables in such a way that EXPLAIN does not need to materialize them. It is possible under certain circumstances that ...
https://dev.mysql.com/doc/refman/8.0/en/descending-indexes.html
row *************************** EXPLAIN: -> Index scan on t1 using a_desc_b_asc (reverse) (cost=0.35 rows=1) See also EXPLAIN Extra Information. MySQL supports descending indexes: DESC in an index definition is no longer ignored but causes storage ...
https://dev.mysql.com/doc/refman/8.0/en/engine-condition-pushdown-optimization.html
Use extended EXPLAIN output to determine which conditions are actually pushed down. An example of such a query, using the table t1 created previously, is shown here: mysql> EXPLAIN -> SELECT * FROM t1 AS x -> LEFT JOIN t1 AS y -> ON x.a=0 AND ...
https://dev.mysql.com/doc/refman/8.0/en/json-search-functions.html
The functions in this section perform search or comparison operations on JSON values to extract data from them, report whether data exists at a location within them, or report the path to data within them. JSON_CONTAINS(target, candidate[, path]) ...
https://dev.mysql.com/doc/refman/8.0/en/order-by-optimization.html
(This is the first table in the EXPLAIN output that does not have a const join type.) The query has different ORDER BY and GROUP BY expressions. ORDER BY Execution Plan Information Available With EXPLAIN (see Section 10.8.1, “Optimizing Queries ...
https://dev.mysql.com/doc/refman/8.0/en/create-table-secondary-indexes.html
A secondary index defined on a virtual column is sometimes referred to as a “virtual index”. A secondary index may be created on one or more virtual columns or on a combination of virtual columns and regular columns or stored generated columns.
https://dev.mysql.com/doc/refman/8.0/en/index-extensions.html
EXPLAIN for the query produces this result: mysql> EXPLAIN SELECT COUNT(*) FROM t1 WHERE i1 = 3 AND d = '2000-01-01'\G *************************** 1. In this case, it can use the leftmost index prefix (d, i1) to produce a better execution plan: ...