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Re: optimizer_switch flags for next 5.3 release



To make it definitive, I am going to perform all future test runs with the following options

ON: derived_merge=ON,derived_with_keys=ON,index_condition_pushdown=ON,mrr=ON,mrr_sort_keys=ON,semijoin=ON,subquery_cache=ON,join_cache_hashed=ON OFF: materialization=OFF,loosescan=OFF,firstmatch=OFF,partial_match*=OFF,join_cache_bka=OFF,mrr_cost_based=OFF

until some other options become ready and available for testing. Materialization requires an audit of pending bugs plus as far as I understood code hacks to disable it for NOT IN, so I am not going to enable it until told otherwise.

Please let me know if I have misunderstood.

Thank you.

Philip Stoev

----- Original Message ----- From: "Sergei Petrunia" <psergey@xxxxxxxxxxxx>
To: <maria-developers@xxxxxxxxxxxxxxxxxxx>
Cc: <timour@xxxxxxxxxxxx>; <igor@xxxxxxxxxxxx>; "Philip Stoev" <pstoev@xxxxxxxxxxxx>; <sanja@xxxxxxxxxxxx>
Sent: Tuesday, October 18, 2011 8:01 PM
Subject: optimizer_switch flags for next 5.3 release


Written down notes from discussion about which flags should be enabled by
default in the next 5.3 release:

- Derived tables and keys in them should be enabled
- BKA should not be enabled (doesn't make sense for 'default' query loads)
- semi-joins should be enabled
- Materialization (base) should be enabled
- extra strategies for NULL-aware materialization - ???
- ICP should be enabled
- Hash join could be enabled but in the next minor release.

- Cost-based MRR should not be enabled as cost model is not tuned.

when some feature is considered stable enough, its owner should apply for
testing with {$current_optimizer_switch_default+new_feature}, and once that is
passed, change the default in the main branch.

Sergei Petrunia, Software Developer
Monty Program AB, http://askmonty.org
Blog: http://s.petrunia.net/blog