MariaDB 5.3 optimizer_switch
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@@optimizer_switch is a server variable that one can use to enable/disable specific optimizations. For generic syntax, see Switchable Optimizations in MySQL Manual.
Below is a list of all @@optimizer_switch flags available in MariaDB 5.3:
| Flag and default setting | Supported in MariaDB since | Supported in MySQL since |
|---|---|---|
derived_merge=off | MariaDB 5.3 | |
derived_with_keys=off | MariaDB 5.3 | |
index_condition_pushdown=off | MariaDB 5.3 | |
index_merge=on | MariaDB 5.1 | MySQL 5.1.x |
index_merge_union=on | MariaDB 5.1 | MySQL 5.1.x |
index_merge_sort_union=on | MariaDB 5.1 | MySQL 5.1.x |
index_merge_intersection=on | MariaDB 5.1 | MySQL 5.1.x |
index_merge_sort_intersection=off | MariaDB 5.3 | |
mrr=off | MariaDB 5.3 | |
mrr_cost_based=off | MariaDB 5.3 | |
mrr_sort_keys=off | MariaDB 5.3 | |
materialization=off | MariaDB 5.3 | |
subquery_cache=off | MariaDB 5.3 | Not supported |
semijoin=off | MariaDB 5.3 | |
firstmatch=off | MariaDB 5.3 | |
loosescan=off | MariaDB 5.3 | |
in_to_exists=on | MariaDB 5.3 | |
partial_match_rowid_merge=on | MariaDB 5.3 | |
partial_match_table_scan=on | MariaDB 5.3 | |
join_cache_bka=on | MariaDB 5.3 | |
join_cache_hashed=on | MariaDB 5.3 | |
join_cache_incremental=on | MariaDB 5.3 | |
outer_join_with_cache=off | MariaDB 5.3 | |
semijoin_with_cache=off | MariaDB 5.3 | |
optimize_join_buffer_size=off | MariaDB 5.3 | |
table_elimination=on | MariaDB 5.1 | Not supported |
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