[wp-trac] [WordPress Trac] #29894: get_terms() isn't caching - duplicate queries generated

[WordPress Trac]

#29894: get_terms() isn't caching - duplicate queries generated
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 Reporter:  webgeekconsulting             |       Owner:  boonebgorges
     Type:  defect (bug)                  |      Status:  accepted
 Priority:  normal                        |   Milestone:  Future Release
Component:  Taxonomy                      |     Version:  4.0
 Severity:  normal                        |  Resolution:
 Keywords:  needs-patch needs-unit-tests  |     Focuses:  performance
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Changes (by boonebgorges):

 * keywords:  has-patch => needs-patch needs-unit-tests
 * milestone:  4.1 => Future Release


Comment:

 webgeekconsulting - Thanks - I'm not sure that update3.diff is the entire
 patch you meant to attach, but I can see enough to understand what you're
 suggesting.

 After further thought, it appears that using merely the SQL to generate a
 cache key is not going to work. `get_terms()` returns different kinds of
 values depending on the value of the 'fields' parameter, but these
 different values come from the same database query. Using the SQL alone to
 create a cache key isn't fine-grained enough.

 I think we have to go with a more conservative approach here. Let's keep
 using the `$args` array to generate the cache key, but let's typecast all
 of the cache keys as necessary. Eg:

 {{{
 $args['hide_empty'] = (bool) $args['hide_empty'];
 }}}

 and so on, with all of the relevant arguments. However, I don't think we
 can safely make these kinds of changes without more complete unit tests,
 because there are places in the function where loose typing is expected -
 see eg https://core.trac.wordpress.org/browser/tags/4.0/src/wp-
 includes/taxonomy.php#L1290.

 I'm attaching a simple unit test that demonstrates the problem as
 originally reported.

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Ticket URL: <https://core.trac.wordpress.org/ticket/29894#comment:10>
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