[wp-trac] [WordPress Trac] #30814: Large wp_postmeta table causes core database queries to become extremely slow.

[WordPress Trac]

#30814: Large wp_postmeta table causes core database queries to become extremely
slow.
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 Reporter:  turkeybucket  |       Owner:
     Type:  defect (bug)  |      Status:  new
 Priority:  normal        |   Milestone:  Awaiting Review
Component:  Query         |     Version:  4.1
 Severity:  normal        |  Resolution:
 Keywords:                |     Focuses:  performance
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Comment (by boonebgorges):

 > One that I consistently showed up had "SQL_CALC_FOUND_ROWS" and "LEFT
 JOIN" and it looked like it was joining the postmeta table

 Unfortunately, this doesn't narrow things down much - most `WP_Query`
 queries look like this. SQL syntax related to the postmeta table was
 changed in a few places in 4.1, but without more data about the specific
 queries that were causing problems in your case, it's hard to guess which,
 if any, is the source of your problem. Are you using any plugins or theme
 customizations that modify the posts that are displayed on archive pages
 or in other loops? Are you doing anything custom with post order/orderby?

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Ticket URL: <https://core.trac.wordpress.org/ticket/30814#comment:4>
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