[wp-trac] [WordPress Trac] #22213: split_the_query breaks posts_distinct filter

[WordPress Trac]

#22213: split_the_query breaks posts_distinct filter
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 Reporter:  johnbillion   |       Owner:
     Type:  defect (bug)  |      Status:  new
 Priority:  normal        |   Milestone:  Awaiting Review
Component:  Query         |     Version:  3.4
 Severity:  normal        |  Resolution:
 Keywords:                |
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Description changed by johnbillion:

Old description:

> If you add a DISTINCT value to a query using the `posts_distinct` filter
> then the functionality which splits a query (#18536) breaks because the
> values from your DISTINCT field are used instead of the ID field.
>
> Example:
>
> {{{
> add_filter( 'posts_distinct', function( $val ) {
>         return 'DISTINCT post_author as pa, ';
> } );
>
> When the split query runs it uses `$wpdb->get_col()` which will return
> the DISTINCT field values we asked for instead of the ID fields. In the
> example above we get an array of post author IDs instead of post IDs.
>
> To get around this problem the split query had to be disabled for this
> request with the `split_the_query` filter.

New description:

 If you add a DISTINCT value to a query using the `posts_distinct` filter
 then the functionality which splits a query (#18536) breaks because the
 values from your DISTINCT field are used instead of the ID field.

 Example:

 {{{
 add_filter( 'posts_distinct', function( $val ) {
         return 'DISTINCT post_author as pa, ';
 } );
 }}}

 When the split query runs it uses `$wpdb->get_col()` which will return the
 DISTINCT field values we asked for instead of the ID fields. In the
 example above we get an array of post author IDs instead of post IDs.

 To get around this problem the split query had to be disabled for this
 request with the `split_the_query` filter.

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Ticket URL: <http://core.trac.wordpress.org/ticket/22213#comment:1>
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