Taxonomy: Force a DISTINCT term query when result count matters.

Generally, duplicate terms returned by a term query are eliminated in PHP,
after the database query takes place. This technique doesn't work properly
when the query parameters specify the `number` of results, since the results
of a `SELECT ... LIMIT x...` query may be deduplicated to a count less than
`x`. In these cases, we force the original query to be `DISTINCT`.

Props elvishp2006.
Fixes #41796.
Built from https://develop.svn.wordpress.org/trunk@41377


git-svn-id: http://core.svn.wordpress.org/trunk@41210 1a063a9b-81f0-0310-95a4-ce76da25c4cd
This commit is contained in:
Boone Gorges 2017-09-13 14:48:45 +00:00
parent 90bedf8f9d
commit 3f7bc21548
2 changed files with 14 additions and 3 deletions

View File

@ -551,6 +551,16 @@ class WP_Term_Query {
$limits = '';
}
$do_distinct = false;
/*
* Duplicate terms are generally removed when necessary after the database query.
* But when a LIMIT clause is included in the query, we let MySQL enforce
* distinctness so the count is correct.
*/
if ( ! empty( $limits ) && 'all_with_object_id' !== $args['fields'] ) {
$do_distinct = true;
}
if ( ! empty( $args['search'] ) ) {
$this->sql_clauses['where']['search'] = $this->get_search_sql( $args['search'] );
@ -568,8 +578,7 @@ class WP_Term_Query {
if ( ! empty( $meta_clauses ) ) {
$join .= $mq_sql['join'];
$this->sql_clauses['where']['meta_query'] = preg_replace( '/^\s*AND\s*/', '', $mq_sql['where'] );
$distinct .= "DISTINCT";
$do_distinct = true;
}
$selects = array();
@ -631,6 +640,8 @@ class WP_Term_Query {
$where = implode( ' AND ', $this->sql_clauses['where'] );
$distinct = $do_distinct ? 'DISTINCT' : '';
/**
* Filters the terms query SQL clauses.
*

View File

@ -4,7 +4,7 @@
*
* @global string $wp_version
*/
$wp_version = '4.9-alpha-41376';
$wp_version = '4.9-alpha-41377';
/**
* Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.