From ef13be6f27ecbcba712ab003d2ced3ae58977d33 Mon Sep 17 00:00:00 2001
From: Boone Gorges <boonebgorges@gmail.com>
Date: Wed, 5 Nov 2014 01:09:21 +0000
Subject: [PATCH] Enforce ORDER BY and LIMIT clauses in `term_exists()`
 queries.

In case of edge cases where a duplicate term might exist in a replicated
database for a split second, these explicit query clauses ensure that
`term_exists()` will always recognize the oldest matched term as the
canonical one. See [30238] for background.

Props pento.
See #22023, #5809.
Built from https://develop.svn.wordpress.org/trunk@30239


git-svn-id: http://core.svn.wordpress.org/trunk@30239 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/taxonomy.php | 10 ++++++----
 wp-includes/version.php  |  2 +-
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/wp-includes/taxonomy.php b/wp-includes/taxonomy.php
index d5f5f33ade..3a9b7c985b 100644
--- a/wp-includes/taxonomy.php
+++ b/wp-includes/taxonomy.php
@@ -2054,6 +2054,8 @@ function term_exists( $term, $taxonomy = '', $parent = null ) {
 	$else_where = 't.name = %s';
 	$where_fields = array($slug);
 	$else_where_fields = array($term);
+	$orderby = 'ORDER BY t.term_id ASC';
+	$limit = 'LIMIT 1';
 	if ( !empty($taxonomy) ) {
 		if ( is_numeric( $parent ) ) {
 			$parent = (int) $parent;
@@ -2066,16 +2068,16 @@ function term_exists( $term, $taxonomy = '', $parent = null ) {
 		$where_fields[] = $taxonomy;
 		$else_where_fields[] = $taxonomy;
 
-		if ( $result = $wpdb->get_row( $wpdb->prepare("SELECT tt.term_id, tt.term_taxonomy_id FROM $wpdb->terms AS t INNER JOIN $wpdb->term_taxonomy as tt ON tt.term_id = t.term_id WHERE $where AND tt.taxonomy = %s", $where_fields), ARRAY_A) )
+		if ( $result = $wpdb->get_row( $wpdb->prepare("SELECT tt.term_id, tt.term_taxonomy_id FROM $wpdb->terms AS t INNER JOIN $wpdb->term_taxonomy as tt ON tt.term_id = t.term_id WHERE $where AND tt.taxonomy = %s $orderby $limit", $where_fields), ARRAY_A) )
 			return $result;
 
-		return $wpdb->get_row( $wpdb->prepare("SELECT tt.term_id, tt.term_taxonomy_id FROM $wpdb->terms AS t INNER JOIN $wpdb->term_taxonomy as tt ON tt.term_id = t.term_id WHERE $else_where AND tt.taxonomy = %s", $else_where_fields), ARRAY_A);
+		return $wpdb->get_row( $wpdb->prepare("SELECT tt.term_id, tt.term_taxonomy_id FROM $wpdb->terms AS t INNER JOIN $wpdb->term_taxonomy as tt ON tt.term_id = t.term_id WHERE $else_where AND tt.taxonomy = %s $orderby $limit", $else_where_fields), ARRAY_A);
 	}
 
-	if ( $result = $wpdb->get_var( $wpdb->prepare("SELECT term_id FROM $wpdb->terms as t WHERE $where", $where_fields) ) )
+	if ( $result = $wpdb->get_var( $wpdb->prepare("SELECT term_id FROM $wpdb->terms as t WHERE $where $orderby $limit", $where_fields) ) )
 		return $result;
 
-	return $wpdb->get_var( $wpdb->prepare("SELECT term_id FROM $wpdb->terms as t WHERE $else_where", $else_where_fields) );
+	return $wpdb->get_var( $wpdb->prepare("SELECT term_id FROM $wpdb->terms as t WHERE $else_where $orderby $limit", $else_where_fields) );
 }
 
 /**
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 9cea8be0d7..bf77663155 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.1-alpha-30238';
+$wp_version = '4.1-alpha-30239';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.