optimizer_switch Helper Functions
You are viewing an old version of this article. View
the current version here.
Syntax
optimizer_switch_on() optimizer_switch_off() optimizer_switch_choice("on" | "off")
Contents
Description
The above procedures can be used to check which optimizer_switch options are on
or off
.
The result set is sorted according to optimizer_switch option name.
Example
select @@optimizer_switch\G *************************** 1. row *************************** index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on, index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on, derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on, in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on, subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on, semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on, optimize_join_buffer_size=on,table_elimination=on,extended_keys=on,exists_to_in=on, orderby_uses_equalities=on,condition_pushdown_for_derived=on,split_materialized=on, condition_pushdown_for_subquery=on,rowid_filter=on,condition_pushdown_from_having=on, not_null_range_scan=off call sys.optimizer_switch_on(); +---------------------------------+------+ | option | opt | +---------------------------------+------+ | condition_pushdown_for_derived | on | | condition_pushdown_for_subquery | on | | condition_pushdown_from_having | on | | derived_merge | on | | derived_with_keys | on | | exists_to_in | on | | extended_keys | on | | firstmatch | on | | index_condition_pushdown | on | | index_merge | on | | index_merge_intersection | on | | index_merge_sort_union | on | | index_merge_union | on | | in_to_exists | on | | join_cache_bka | on | | join_cache_hashed | on | | join_cache_incremental | on | | loosescan | on | | materialization | on | | optimize_join_buffer_size | on | | orderby_uses_equalities | on | | outer_join_with_cache | on | | partial_match_rowid_merge | on | | partial_match_table_scan | on | | rowid_filter | on | | semijoin | on | | semijoin_with_cache | on | | split_materialized | on | | subquery_cache | on | | table_elimination | on | +---------------------------------+------+ call sys.optimizer_switch_off(); +-------------------------------+------+ | option | opt | +-------------------------------+------+ | engine_condition_pushdown | off | | index_merge_sort_intersection | off | | mrr | off | | mrr_cost_based | off | | mrr_sort_keys | off | | not_null_range_scan | off | +-------------------------------+------+
Notes
sys.optimizer_switch_on()
is a shortcut for sys.optimizer_switch_choice("on")
;
sys.optimizer_switch_off()
is a shortcut for sys.optimizer_switch_choice("off")
;
See Also
- optimizer-switch Documentation for optimizer_switch
Comments
Comments loading...
Content reproduced on this site is the property of its respective owners,
and this content is not reviewed in advance by MariaDB. The views, information and opinions
expressed by this content do not necessarily represent those of MariaDB or any other party.