[wp-trac] [WordPress Trac] #38173: Meta query creates unecessary multiple left joins when using the same meta key

[WordPress Trac]

#38173: Meta query creates unecessary multiple left joins when using the same meta
key
--------------------------+------------------------------
 Reporter:  neonWired     |       Owner:
     Type:  defect (bug)  |      Status:  new
 Priority:  normal        |   Milestone:  Awaiting Review
Component:  Database      |     Version:  4.6
 Severity:  normal        |  Resolution:
 Keywords:                |     Focuses:  performance
--------------------------+------------------------------

Comment (by tamiassibiricus):

 Got same situation when have about 10000 posts in WP setup and need to
 filter by meta that filled for all posts quantity(each post have value for
 meta). So we have same meta qty that could joined twice or more.
 When mysql join meta vertical tables it join each 10000 records and then
 shrink results by conditions placed in Where section.
 it could really slow down mysql selects at first run.
 working and tested solution -
 https://gist.github.com/TamiasSibiricus/917b3dfc2b13b97e644ea739a1a1a306

--
Ticket URL: <https://core.trac.wordpress.org/ticket/38173#comment:1>
WordPress Trac <https://core.trac.wordpress.org/>
WordPress publishing platform