REST API: Improve performance of X-WP-Total/X-WP-TotalPages queries.

Improve the performance of fallback queries to determine the total number of objects available on various REST endpoints for out of bounds queries.

The database queries are modified to return the minimum amount of data required for determining the count and bypass priming of meta a term caches where appropriate.

Props adamsilverstein, joehoyle, johnbillion, jorbin, kadamwhite, spacedmonkey, sukhendu2002, westonruter.
Fixes #62801.


git-svn-id: https://develop.svn.wordpress.org/trunk@61002 602fd350-edb4-49c9-b593-d223f7449a82

Author: peterwilsoncc

src/wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php

@@ -323,12 +323,13 @@ public function get_items( $request ) {
 		$max_pages      = (int) $query->max_num_pages;
 
 		if ( $total_comments < 1 ) {
-			// Out-of-bounds, run the query again without LIMIT for total count.
+			// Out-of-bounds, run the query without pagination/offset to get the total count.
 			unset( $prepared_args['number'], $prepared_args['offset'] );
 
-			$query                    = new WP_Comment_Query();
-			$prepared_args['count']   = true;
-			$prepared_args['orderby'] = 'none';
+			$query                                      = new WP_Comment_Query();
+			$prepared_args['count']                     = true;
+			$prepared_args['orderby']                   = 'none';
+			$prepared_args['update_comment_meta_cache'] = false;
 
 			$total_comments = $query->query( $prepared_args );
 			$max_pages      = (int) ceil( $total_comments / $request['per_page'] );

src/wp-includes/rest-api/endpoints/class-wp-rest-global-styles-revisions-controller.php

@@ -203,9 +203,15 @@ public function get_items( $request ) {
 			$total_revisions = $revisions_query->found_posts;
 
 			if ( $total_revisions < 1 ) {
-				// Out-of-bounds, run the query again without LIMIT for total count.
+				// Out-of-bounds, run the query without pagination/offset to get the total count.
 				unset( $query_args['paged'], $query_args['offset'] );
-				$count_query = new WP_Query();
+
+				$count_query                          = new WP_Query();
+				$query_args['fields']                 = 'ids';
+				$query_args['posts_per_page']         = 1;
+				$query_args['update_post_meta_cache'] = false;
+				$query_args['update_post_term_cache'] = false;
+
 				$count_query->query( $query_args );
 
 				$total_revisions = $count_query->found_posts;

src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php

@@ -487,10 +487,15 @@ static function ( $format ) {
 		$total_posts = $posts_query->found_posts;
 
 		if ( $total_posts < 1 && $page > 1 ) {
-			// Out-of-bounds, run the query again without LIMIT for total count.
+			// Out-of-bounds, run the query without pagination/offset to get the total count.
 			unset( $query_args['paged'] );
 
-			$count_query = new WP_Query();
+			$count_query                          = new WP_Query();
+			$query_args['fields']                 = 'ids';
+			$query_args['posts_per_page']         = 1;
+			$query_args['update_post_meta_cache'] = false;
+			$query_args['update_post_term_cache'] = false;
+
 			$count_query->query( $query_args );
 			$total_posts = $count_query->found_posts;
 		}

src/wp-includes/rest-api/endpoints/class-wp-rest-revisions-controller.php

@@ -308,12 +308,16 @@ public function get_items( $request ) {
 			$total_revisions = $revisions_query->found_posts;
 
 			if ( $total_revisions < 1 ) {
-				// Out-of-bounds, run the query again without LIMIT for total count.
+				// Out-of-bounds, run the query without pagination/offset to get the total count.
 				unset( $query_args['paged'], $query_args['offset'] );
 
-				$count_query = new WP_Query();
-				$count_query->query( $query_args );
+				$count_query                          = new WP_Query();
+				$query_args['fields']                 = 'ids';
+				$query_args['posts_per_page']         = 1;
+				$query_args['update_post_meta_cache'] = false;
+				$query_args['update_post_term_cache'] = false;
 
+				$count_query->query( $query_args );
 				$total_revisions = $count_query->found_posts;
 			}
 

src/wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php

@@ -399,10 +399,13 @@ static function ( $column ) use ( $search_columns_mapping ) {
 		$total_users = $query->get_total();
 
 		if ( $total_users < 1 ) {
-			// Out-of-bounds, run the query again without LIMIT for total count.
+			// Out-of-bounds, run the query without pagination/offset to get the total count.
 			unset( $prepared_args['number'], $prepared_args['offset'] );
-			$count_query = new WP_User_Query( $prepared_args );
-			$total_users = $count_query->get_total();
+
+			$prepared_args['number'] = 1;
+			$prepared_args['fields'] = 'ID';
+			$count_query             = new WP_User_Query( $prepared_args );
+			$total_users             = $count_query->get_total();
 		}
 
 		$response->header( 'X-WP-Total', (int) $total_users );