Remove MySQL's optimizer switch and investigate benefits of BNL and BKA optimizer hints
|Assignee:||Steve Breker||% Done:|
|Google Code Legacy ID:||Tested version:||2.6|
MySQL 8 introduced changes in the
block_nested_loop optimizer switch:
block_nested_loop (default on)
Controls use of BNL join algorithm. In MySQL 8.0.18 and later, this also controls use of hash joins. In MySQL 8.0.20 and later, block nested loop support is removed from the MySQL server, and this flag no longer has any effect; use the BNL or NO_BNL optimizer hint instead, to control whether hash joins are used.
The BNL, NO_BNL and BKA, NO_BKA optimizer hints have to be applied at the statement level, so we should investigate in what queries do they have an impact instead of globally applying the no longer considered
block_nested_loop optimizer switch.