Split the main WP_Query posts query into two queries to avoid temp tables. Leverage cache to avoid second query in persistent cache environments. Props scribu, cheald, prettyboymp. see #18536

git-svn-id: http://svn.automattic.com/wordpress/trunk@19918 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/functions.php

@@ -3703,3 +3703,26 @@ function wp_debug_backtrace_summary( $ignore_class = null, $skip_frames = 0, $pr
 	else
 		return $caller;
 }
+
+/**
+ * Retrieve ids that are not already present in the cache
+ *
+ * @since 3.4.0
+ *
+ * @param array $object_ids ID list
+ * @param string $cache_key The cache bucket to check against
+ *
+ * @return array
+ */
+function _get_non_cached_ids( $object_ids, $cache_key ) {
+	$clean = array();
+	foreach ( $object_ids as $id ) {
+		$id = (int) $id;
+		if ( !wp_cache_get( $id, $cache_key ) ) {
+			$clean[] = $id;
+		}
+	}
+
+	return $clean;
+}
+

wp-includes/pluggable.php

@@ -139,13 +139,7 @@ if ( !function_exists('cache_users') ) :
 function cache_users( $user_ids ) {
 	global $wpdb;
 
-	$clean = array();
-	foreach ( $user_ids as $id ) {
-		$id = (int) $id;
-		if ( !wp_cache_get( $id, 'users' ) ) {
-			$clean[] = $id;
-		}
-	}
+	$clean = _get_non_cached_ids( $user_ids, 'users' );
 
 	if ( empty( $clean ) )
 		return;

wp-includes/post-thumbnail-template.php

@@ -64,13 +64,7 @@ function update_post_thumbnail_cache() {
 	}
 
 	if ( ! empty ( $thumb_ids ) ) {
-		get_posts( array(
-				'update_post_term_cache' => false,
-				'include' => $thumb_ids,
-				'post_type' => 'attachment',
-				'post_status' => 'inherit',
-				'nopaging' => true
-		) );
+		_prime_post_caches( $thumb_ids, false, true );
 	}
 
 	$wp_query->thumbnails_cached = true;

wp-includes/post.php

@@ -5318,3 +5318,26 @@ function _update_term_count_on_transition_post_status( $new_status, $old_status,
 		wp_update_term_count( $tt_ids, $taxonomy );
 	}
 }
+
+/**
+ * Adds any posts from the given ids to the cache that do not already exist in cache
+ *
+ * @since 3.4.0
+ *
+ * @access private
+ *
+ * @param array $post_ids ID list
+ * @param bool $update_term_cache Whether to update the term cache. Default is true.
+ * @param bool $update_meta_cache Whether to update the meta cache. Default is true.
+ */
+function _prime_post_caches( $ids, $update_term_cache = true, $update_meta_cache = true ) {
+	global $wpdb;
+
+	$non_cached_ids = _get_non_cached_ids( $ids, 'posts' );
+	if ( !empty( $non_cached_ids ) ) {
+		$fresh_posts = $wpdb->get_results( sprintf( "SELECT $wpdb->posts.* FROM $wpdb->posts WHERE ID IN (%s)", join( ",", $non_cached_ids ) ) );
+
+		update_post_caches( $fresh_posts, 'any', $update_term_cache, $update_meta_cache );
+	}
+}
+

wp-includes/query.php

@@ -2606,9 +2606,11 @@ class WP_Query {
 		if ( !$q['no_found_rows'] && !empty($limits) )
 			$found_rows = 'SQL_CALC_FOUND_ROWS';
 
-		$this->request = " SELECT $found_rows $distinct $fields FROM $wpdb->posts $join WHERE 1=1 $where $groupby $orderby $limits";
-		if ( !$q['suppress_filters'] )
-			$this->request = apply_filters_ref_array('posts_request', array( $this->request, &$this ) );
+		$this->request = $old_request = "SELECT $found_rows $distinct $fields FROM $wpdb->posts $join WHERE 1=1 $where $groupby $orderby $limits";
+
+		if ( !$q['suppress_filters'] ) {
+			$this->request = apply_filters( 'posts_request', $this->request, $this );
+		}
 
 		if ( 'ids' == $q['fields'] ) {
 			$this->posts = $wpdb->get_col($this->request);
@@ -2626,7 +2628,29 @@ class WP_Query {
 			return $r;
 		}
 
-		$this->posts = $wpdb->get_results($this->request);
+		if ( $old_request == $this->request && "$wpdb->posts.*" == $fields ) {
+			// First get the IDs and then fill in the objects
+
+			$this->request = "SELECT $found_rows $distinct $wpdb->posts.ID FROM $wpdb->posts $join WHERE 1=1 $where $groupby $orderby $limits";
+
+			$this->request = apply_filters( 'posts_request_ids', $this->request, $this );
+
+			$ids = $wpdb->get_col( $this->request );
+
+			if ( $ids ) {
+				$this->set_found_posts( $q, $limits );
+
+				_prime_post_caches( $ids, $q['update_post_term_cache'], $q['update_post_meta_cache'] );
+
+				$this->posts = array_map( 'get_post', $ids );
+			} else {
+				$this->found_posts = $this->max_num_pages = 0;
+				$this->posts = array();
+			}
+		} else {
+			$this->posts = $wpdb->get_results( $this->request );
+			$this->set_found_posts( $q, $limits );
+		}
 
 		// Raw results filter. Prior to status checks.
 		if ( !$q['suppress_filters'] )
@@ -2645,13 +2669,6 @@ class WP_Query {
 			$this->comment_count = count($this->comments);
 		}
 
-		if ( !$q['no_found_rows'] && !empty($limits) ) {
-			$found_posts_query = apply_filters_ref_array( 'found_posts_query', array( 'SELECT FOUND_ROWS()', &$this ) );
-			$this->found_posts = $wpdb->get_var( $found_posts_query );
-			$this->found_posts = apply_filters_ref_array( 'found_posts', array( $this->found_posts, &$this ) );
-			$this->max_num_pages = ceil($this->found_posts / $q['posts_per_page']);
-		}
-
 		// Check post status to determine if post should be displayed.
 		if ( !empty($this->posts) && ($this->is_single || $this->is_page) ) {
 			$status = get_post_status($this->posts[0]);
@@ -2754,6 +2771,18 @@ class WP_Query {
 		return $this->posts;
 	}
 
+	function set_found_posts( $q, $limits ) {
+		global $wpdb;
+
+		if ( $q['no_found_rows'] || empty( $limits ) )
+			return;
+
+		$this->found_posts = $wpdb->get_var( apply_filters( 'found_posts_query', 'SELECT FOUND_ROWS()', $this ) );
+		$this->found_posts = apply_filters( 'found_posts', $this->found_posts, $this );
+
+		$this->max_num_pages = ceil( $this->found_posts / $q['posts_per_page'] );
+	}
+
 	/**
 	 * Set up the next post and iterate current post index.
 	 *