PDF (US Ltr)
- 43.3Mb
PDF (A4)
- 43.4Mb
Man Pages (TGZ)
- 296.6Kb
Man Pages (Zip)
- 402.0Kb
Info (Gzip)
- 4.3Mb
Info (Zip)
- 4.3Mb
Search Results
https://dev.mysql.com/doc/refman/8.0/en/join.html
MySQL supports the following JOIN syntax for the table_references part of SELECT statements and multiple-table DELETE and UPDATE statements: table_references: escaped_table_reference [, escaped_table_reference] ... index_hint: { USE {INDEX|KEY} ...
https://dev.mysql.com/doc/refman/8.0/en/nested-join-optimization.html
The following discussion refers to the join syntax described in Section 15.2.13.2, “JOIN Clause”. This is a conservative extension if we consider each comma in a list of table_reference items as equivalent to an inner join. INNER JOIN is used ...
https://dev.mysql.com/doc/refman/8.0/en/hash-joins.html
By default, MySQL (8.0.18 and later) employs hash joins whenever possible. 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 ...
https://dev.mysql.com/doc/refman/8.0/en/outer-join-simplification.html
At the parser stage, queries with right outer join operations are converted to equivalent queries containing only left join operations. When the optimizer evaluates plans for outer join operations, it takes into consideration only plans where, for ... Table expressions in the FROM clause of a query are simplified in many ...
https://dev.mysql.com/doc/refman/8.0/en/nested-loop-joins.html
MySQL executes joins between tables using a nested-loop algorithm or variations on it. Nested-Loop Join Algorithm Block Nested-Loop Join Algorithm Nested-Loop Join Algorithm A simple nested-loop join (NLJ) algorithm reads rows from the first table ...For example, if 10 rows are read into a buffer and the buffer is passed to the next inner loop, each row read in the inner loop can be compared against all 10 rows in the ...
https://dev.mysql.com/doc/refman/8.0/en/bnl-bka-optimization.html
In MySQL, a Batched Key Access (BKA) Join algorithm is available that uses both index access to the joined table and a join buffer. The BKA algorithm supports inner join, outer join, and semijoin operations, including nested outer joins. Benefits ...That is, it is incremental to a row from the first operand ...
https://dev.mysql.com/doc/refman/8.0/en/outer-join-optimization.html
MySQL implements an A LEFT JOIN B join_specification as follows: Table B is set to depend on table A and all tables on which A depends. Table A is set to depend on all tables (except B) that are used in the LEFT JOIN condition. The LEFT JOIN ...If ...
https://dev.mysql.com/doc/refman/8.0/en/group-replication-system-variables.html
If a running group has a value set for a group-wide configuration setting, and a joining member has a different value set for that system variable, the joining member cannot join the group until the value is changed to match. If the group has a ...
https://dev.mysql.com/doc/refman/8.0/en/mysql-nutshell.html
Beginning with MySQL 8.0.16, the semijoin optimizations used with IN subqueries can now be applied to EXISTS subqueries as well. For more information, see Section 10.2.2.1, “Optimizing IN and EXISTS Subquery Predicates with Semijoin ... This ...
https://dev.mysql.com/doc/refman/8.0/en/explain-output.html
EXPLAIN Output Columns EXPLAIN Join Types EXPLAIN Extra Information EXPLAIN Output Interpretation EXPLAIN Output Columns This section describes the output columns produced by EXPLAIN. rows shows the estimated number of rows examined and rows × ...