From: Kevin Israel <pleasestand@live.com>
Date: Fri, 28 Aug 2015 07:57:01 +0000 (-0400)
Subject: Avoid creating lots and lots of cat_id gaps
X-Git-Tag: 1.31.0-rc.0~9363
X-Git-Url: https://git.cyclocoop.org/%27.WWW_URL.%27admin/?a=commitdiff_plain;h=aebdfef5fefad48c56a2583f8a2f8e86ee90124e;p=lhc%2Fweb%2Fwiklou.git

Avoid creating lots and lots of cat_id gaps

Currently, INSERT...ON DUPLICATE KEY UPDATE is used to update the page
counts in the category table. However, MySQL 5.1.22 and newer, by default,
increment the counter for cat_id before checking for duplicate key errors.
This creates many gaps in the cat_id sequence.

To avoid this, check for existing category rows, and instead UPDATE any
that were found. It is hoped that the extra queries will not significantly
harm performance.

Change-Id: Ic2ab9ff14f04a0c7ea90a5b6756cade0c78e2885
---

diff --git a/includes/Category.php b/includes/Category.php
index c3e8a4eb4e..1b05f33a96 100644
--- a/includes/Category.php
+++ b/includes/Category.php
@@ -304,11 +304,11 @@ class Category {
 			return false;
 		}
 
-		# Note, we must use names for this, since categorylinks does.
-		if ( $this->mName === null ) {
-			if ( !$this->initialize() ) {
-				return false;
-			}
+		# If we have just a category name, find out whether there is an
+		# existing row. Or if we have just an ID, get the name, because
+		# that's what categorylinks uses.
+		if ( !$this->initialize() ) {
+			return false;
 		}
 
 		$dbw = wfGetDB( DB_MASTER );
@@ -327,25 +327,38 @@ class Category {
 			array( 'LOCK IN SHARE MODE' )
 		);
 
-		# TODO: This will cause lots and lots of gaps on MySQL unless
-		# innodb_autoinc_lock_mode is 0 (and also on some non-MySQL
-		# DBMSes) if you run populateCategory.php repeatedly.
-		$dbw->upsert(
-			'category',
-			array(
-				'cat_title' => $this->mName,
-				'cat_pages' => $result->pages,
-				'cat_subcats' => $result->subcats,
-				'cat_files' => $result->files
-			),
-			array( 'cat_title' ),
-			array(
-				'cat_pages' => $result->pages,
-				'cat_subcats' => $result->subcats,
-				'cat_files' => $result->files
-			),
-			__METHOD__
-		);
+		if ( $this->mId ) {
+			# The category row already exists, so do a plain UPDATE instead
+			# of INSERT...ON DUPLICATE KEY UPDATE to avoid creating a gap
+			# in the cat_id sequence. The row may or may not be "affected".
+			$dbw->update(
+				'category',
+				array(
+					'cat_pages' => $result->pages,
+					'cat_subcats' => $result->subcats,
+					'cat_files' => $result->files
+				),
+				array( 'cat_title' => $this->mName ),
+				__METHOD__
+			);
+		} else {
+			$dbw->upsert(
+				'category',
+				array(
+					'cat_title' => $this->mName,
+					'cat_pages' => $result->pages,
+					'cat_subcats' => $result->subcats,
+					'cat_files' => $result->files
+				),
+				array( 'cat_title' ),
+				array(
+					'cat_pages' => $result->pages,
+					'cat_subcats' => $result->subcats,
+					'cat_files' => $result->files
+				),
+				__METHOD__
+			);
+		}
 
 		$dbw->endAtomic( __METHOD__ );
 
diff --git a/includes/page/WikiPage.php b/includes/page/WikiPage.php
index 3f6a4db3cf..3ec3e89bf9 100644
--- a/includes/page/WikiPage.php
+++ b/includes/page/WikiPage.php
@@ -3395,22 +3395,44 @@ class WikiPage implements Page, IDBAccessObject {
 				}
 
 				if ( count( $added ) ) {
-					$insertRows = array();
-					foreach ( $added as $cat ) {
-						$insertRows[] = array(
-							'cat_title'   => $cat,
-							'cat_pages'   => 1,
-							'cat_subcats' => ( $ns == NS_CATEGORY ) ? 1 : 0,
-							'cat_files'   => ( $ns == NS_FILE ) ? 1 : 0,
-						);
-					}
-					$dbw->upsert(
+					$existingAdded = $dbw->selectFieldValues(
 						'category',
-						$insertRows,
-						array( 'cat_title' ),
-						$addFields,
-						$method
+						'cat_title',
+						array( 'cat_title' => $added ),
+						__METHOD__
 					);
+
+					// For category rows that already exist, do a plain
+					// UPDATE instead of INSERT...ON DUPLICATE KEY UPDATE
+					// to avoid creating gaps in the cat_id sequence.
+					if ( count( $existingAdded ) ) {
+						$dbw->update(
+							'category',
+							$addFields,
+							array( 'cat_title' => $existingAdded ),
+							__METHOD__
+						);
+					}
+
+					$missingAdded = array_diff( $added, $existingAdded );
+					if ( count( $missingAdded ) ) {
+						$insertRows = array();
+						foreach ( $missingAdded as $cat ) {
+							$insertRows[] = array(
+								'cat_title'   => $cat,
+								'cat_pages'   => 1,
+								'cat_subcats' => ( $ns == NS_CATEGORY ) ? 1 : 0,
+								'cat_files'   => ( $ns == NS_FILE ) ? 1 : 0,
+							);
+						}
+						$dbw->upsert(
+							'category',
+							$insertRows,
+							array( 'cat_title' ),
+							$addFields,
+							$method
+						);
+					}
 				}
 
 				if ( count( $deleted ) ) {