maria-developers team mailing list archive

[Sergey Petrunya <psergey@xxxxxxxxxxxx>]

Hello,

Following what has been decided on the optimizer call, I'm nearly done with 
making semi-join optimizations off by default in 5.3. However, some of 5.3's
new optimizations are still turned on by default.

Here is a list of 5.3 features and flags that control them:

index_merge_sort_intersection=off

semijoin=off
firstmatch=off
loosescan=off
  ^^ just done the above.

materialization=off
  
derived_merge=on
derived_with_keys=on
  ^^ Are we sure about this? 

index_condition_pushdown=on
  ^^ This needs to be discussed too.

partial_match_rowid_merge=on
partial_match_table_scan=on
  ^^ These are still off because materialization is off.

subquery_cache=on
  ^^ Need to discuss this.

mrr=on
mrr_cost_based=off
mrr_sort_keys=on
  ^^ Need to discuss this. I take we should disable MRR, too (since BKA is
  disabled anyway?)

join_cache_incremental=on
join_cache_hashed=on
join_cache_bka=on
optimize_join_buffer_size=on 
  ^^ These are not really on because default join_cache_level setting prevents
     any of these from being used.


Another question is that we *MUST* have documentation in place if we're making
a release with features that are disabled by default.


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