From c27d7049999037bb131ab2e59e28feafcd8fb55c Mon Sep 17 00:00:00 2001
From: scribu <scribu@1a063a9b-81f0-0310-95a4-ce76da25c4cd>
Date: Mon, 6 Sep 2010 11:04:50 +0000
Subject: [PATCH] Use multiple JOINs instead of CASE in _wp_meta_sql(). See
 #14572

git-svn-id: http://svn.automattic.com/wordpress/trunk@15580 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/functions.php | 45 +++++++++++++++++++++++++--------------
 wp-includes/user.php      |  9 +++-----
 2 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index 23f70f137f..b598161dc0 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -4243,10 +4243,13 @@ function _wp_search_sql($string, $cols) {
  * @since 3.1.0
  *
  * @param array $queries An array of queries
- * @param string $meta_id_column The column that holds the object id
- * @return string
+ * @param string $primary_table
+ * @param string $primary_id_column
+ * @param string $meta_table
+ * @param string $meta_id_column
+ * @return array( $join_sql, $where_sql )
  */
-function _wp_meta_sql( $queries, $meta_id_column ) {
+function _wp_meta_sql( $queries, $primary_table, $primary_id_column, $meta_table, $meta_id_column ) {
 	global $wpdb;
 
 	$clauses = array();
@@ -4262,29 +4265,39 @@ function _wp_meta_sql( $queries, $meta_id_column ) {
 		if ( empty( $meta_key ) )
 			continue;
 
-		$clause = $wpdb->prepare( "WHEN %s THEN meta_value ", $meta_key );
-
 		if ( empty( $meta_value ) ) {
-			$clauses[] = $clause . "IS NOT NULL";
+			$clauses[ $meta_key ] = "";
 		} elseif ( 'like' == $meta_compare ) {
-			$clauses[] = $clause . $wpdb->prepare( "LIKE %s", '%' . like_escape( $meta_value ) . '%' );
+			$clauses[ $meta_key ] = $wpdb->prepare( "LIKE %s", '%' . like_escape( $meta_value ) . '%' );
 		} else {
-			$clauses[] = $clause . $wpdb->prepare( "$meta_compare %s", $meta_value );
+			$clauses[ $meta_key ] = $wpdb->prepare( "$meta_compare %s", $meta_value );
 		}
 	}
 
 	if ( empty( $clauses ) )
-		return '';
+		return array('', '');
 
-	return "
-		AND CASE meta_key 
-		" . implode( "\n", $clauses ) . "
-		END
-		GROUP BY $meta_id_column
-		HAVING COUNT(*) = " . count( $clauses );
+	$join = '';
+	$where = '';
+
+	$i = 0;
+	foreach ( $clauses as $meta_key => $value_query ) {
+		$alias = $i ? 'mt' . $i : $meta_table;
+
+		$join .= "\nINNER JOIN $meta_table";
+		$join .= $i ? " AS $alias" : '';
+		$join .= " ON ($primary_table.$primary_id_column = $alias.$meta_id_column)";
+
+		$where .= $wpdb->prepare( " AND $alias.meta_key = %s", $meta_key );
+		if ( !empty( $value_query ) )
+			$where .= " AND $alias.meta_value $value_query";
+			
+		$i++;
+	}
+
+	return array( $join, $where );
 }
 
-
 /*
  * Used internally to tidy up the search terms
  *
diff --git a/wp-includes/user.php b/wp-includes/user.php
index 5dfce4ae17..5deab86687 100644
--- a/wp-includes/user.php
+++ b/wp-includes/user.php
@@ -463,12 +463,9 @@ class WP_User_Query {
 
 		$meta_queries[] = wp_array_slice_assoc( $qv, array( 'meta_key', 'meta_value', 'meta_compare' ) );
 
-		$meta_query_sql = _wp_meta_sql( $meta_queries, 'user_id' );
-
-		if ( !empty( $meta_query_sql ) ) {
-			$this->query_from .= " INNER JOIN $wpdb->usermeta ON ($wpdb->users.ID = $wpdb->usermeta.user_id)";
-			$this->query_where .= $meta_query_sql;
-		}
+		list( $meta_join, $meta_where ) = _wp_meta_sql( $meta_queries, $wpdb->users, 'ID', $wpdb->usermeta, 'user_id' );
+		$this->query_from .= $meta_join;
+		$this->query_where .= $meta_where;
 
 		if ( !empty($qv['include']) ) {
 			$ids = implode( ',', wp_parse_id_list( $qv['include'] ) );