From 6d1c7c414b694c31e44ba3c88d94a8f0a2ae1e19 Mon Sep 17 00:00:00 2001
From: Daku <admin@codeanimu.net>
Date: Fri, 4 Dec 2015 11:38:44 +0000
Subject: [PATCH] mysql < 5.6 has terrible subquery optimization, using EXISTS
 / JOIN fixes this

---
 core/imageboard.pack.php | 19 ++++++++++++++++---
 ext/index/main.php       | 20 ++++++++++++++------
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/core/imageboard.pack.php b/core/imageboard.pack.php
index e27bc7a0..1d8365f7 100644
--- a/core/imageboard.pack.php
+++ b/core/imageboard.pack.php
@@ -560,9 +560,22 @@ class Image {
 	 */
 	public function delete_tags_from_image() {
 		global $database;
-		$database->execute(
-				"UPDATE tags SET count = count - 1 WHERE id IN ".
-				"(SELECT tag_id FROM image_tags WHERE image_id = :id)", array("id"=>$this->id));
+		if($database->get_driver_name() == "mysql") {
+			//mysql < 5.6 has terrible subquery optimization, using EXISTS / JOIN fixes this
+			$database->execute("
+				UPDATE tags t
+				INNER JOIN image_tags it ON t.id = it.tag_id
+				SET count = count - 1
+				WHERE it.image_id = :id",
+				array("id"=>$this->id)
+			);
+		} else {
+			$database->execute("
+				UPDATE tags
+				SET count = count - 1
+				WHERE id IN (SELECT tag_id FROM image_tags WHERE image_id = :id)", array("id"=>$this->id)
+			);
+		}
 		$database->execute("DELETE FROM image_tags WHERE image_id=:id", array("id"=>$this->id));
 	}
 
diff --git a/ext/index/main.php b/ext/index/main.php
index 75a7fab0..78404fe6 100644
--- a/ext/index/main.php
+++ b/ext/index/main.php
@@ -253,9 +253,9 @@ class Index extends Extension {
 			$search_terms = $event->get_search_terms();
 			$page_number = $event->get_page_number();
 			$page_size = $event->get_page_size();
-            
+
 			$count_search_terms = count($search_terms);
-            
+
 			try {
 				#log_debug("index", "Search for ".implode(" ", $search_terms), false, array("terms"=>$search_terms));
 				$total_pages = Image::count_pages($search_terms);
@@ -277,7 +277,7 @@ class Index extends Extension {
 			}
 
 			$count_images = count($images);
-            
+
 			if($count_search_terms === 0 && $count_images === 0 && $page_number === 1) {
 				$this->theme->display_intro($page);
 				send_event(new PostListBuildingEvent($search_terms));
@@ -322,8 +322,17 @@ class Index extends Extension {
 		// check for tags first as tag based searches are more common.
 		if(preg_match("/^tags([:]?<|[:]?>|[:]?<=|[:]?>=|[:|=])(\d+)$/i", $event->term, $matches)) {
 			$cmp = ltrim($matches[1], ":") ?: "=";
-			$tags = $matches[2];
-			$event->add_querylet(new Querylet('images.id IN (SELECT DISTINCT image_id FROM image_tags GROUP BY image_id HAVING count(image_id) '.$cmp.' '.$tags.')'));
+			$count = $matches[2];
+			$event->add_querylet(
+				new Querylet("EXISTS (
+				              SELECT 1
+				              FROM image_tags it
+				              LEFT JOIN tags t ON it.tag_id = t.id
+				              WHERE images.id = it.image_id
+				              GROUP BY image_id
+				              HAVING COUNT(*) $cmp $count
+				)")
+			);
 		}
 		else if(preg_match("/^ratio([:]?<|[:]?>|[:]?<=|[:]?>=|[:|=])(\d+):(\d+)$/i", $event->term, $matches)) {
 			$cmp = preg_replace('/^:/', '=', $matches[1]);
@@ -394,4 +403,3 @@ class Index extends Extension {
 		$this->stpen++;
 	}
 }
-