[wp-trac] [WordPress Trac] #36343: Taxonomy query matching specified term or NOT EXISTS does not return expected result

[WordPress Trac]

#36343: Taxonomy query matching specified term or NOT EXISTS does not return
expected result
------------------------------------------------+--------------------------
 Reporter:  crstauf                             |       Owner:
     Type:  defect (bug)                        |      Status:  new
 Priority:  normal                              |   Milestone:  Future
Component:  Query                               |  Release
 Severity:  normal                              |     Version:  4.1
 Keywords:  has-patch has-unit-tests 4.6-early  |  Resolution:
                                                |     Focuses:
------------------------------------------------+--------------------------
Changes (by boonebgorges):

 * keywords:  has-patch has-unit-tests => has-patch has-unit-tests 4.6-early


Comment:

 @crstauf Thanks very much for your help debugging this, and for verifying
 @swissspidy's suggested fix.

 @swissspidy Your diagnosis sounds correct. #29062 was a very similar
 problem, fixed in a similar way in [29890]. My one thought is that perhaps
 we should only use `LEFT JOIN` when we know that `NOT EXISTS` is used in a
 given clause. `INNER JOIN` gives the MySQL optimizer more flexibility when
 deciding the order in which to read the tables, which could result in
 performance improvements in some cases. (Could someone with more knowledge
 than me of the optimizer internals verify this line of reasoning? cough
 @pento cough)

--
Ticket URL: <https://core.trac.wordpress.org/ticket/36343#comment:8>
WordPress Trac <https://core.trac.wordpress.org/>
WordPress publishing platform