From 52b1b6e9c332faf9dfd1aac60bdede2c00e0836d Mon Sep 17 00:00:00 2001
From: Brion Vibber <brion@users.mediawiki.org>
Date: Thu, 9 Sep 2004 00:02:38 +0000
Subject: [PATCH] Add Database::conditional() function to build IF() or CASE
 statements depending on the RDBMS used. Allowed NULL in some RC fields on
 PostgreSQL.

Fix for bug 407: rebuildrecentchanges.php fails on PostgreSQL
http://bugzilla.wikipedia.org/show_bug.cgi?id=407
---
 includes/Database.php                | 13 +++++++++++++
 includes/DatabasePostgreSQL.php      | 13 +++++++++++++
 maintenance/postgresql/pg_tables.sql |  4 ++--
 maintenance/rebuildrecentchanges.inc | 20 +++++++++++---------
 4 files changed, 39 insertions(+), 11 deletions(-)

diff --git a/includes/Database.php b/includes/Database.php
index c2d87301cc..d9ab045719 100644
--- a/includes/Database.php
+++ b/includes/Database.php
@@ -1041,6 +1041,19 @@ class Database {
 		return ' LIMIT '.(is_numeric($offset)?"{$offset},":"")."{$limit} ";
 	}
 
+	/**
+	 * Returns an SQL expression for a simple conditional.
+	 * Uses IF on MySQL.
+	 *
+	 * @param string $cond SQL expression which will result in a boolean value
+	 * @param string $trueVal SQL expression to return if true
+	 * @param string $falseVal SQL expression to return if false
+	 * @return string SQL fragment
+	 */
+	function conditional( $cond, $trueVal, $falseVal ) {
+		return " IF($cond, $trueVal, $falseVal) ";
+	}
+
 	/**
 	 * @todo document
 	 */
diff --git a/includes/DatabasePostgreSQL.php b/includes/DatabasePostgreSQL.php
index db4c7d8454..75c7fe4808 100644
--- a/includes/DatabasePostgreSQL.php
+++ b/includes/DatabasePostgreSQL.php
@@ -351,6 +351,19 @@ class DatabasePgsql extends Database {
 	function limitResult($limit,$offset) {
         	return " LIMIT $limit ".(is_numeric($offset)?" OFFSET {$offset} ":"");
 	}
+	
+	/**
+	 * Returns an SQL expression for a simple conditional.
+	 * Uses CASE on PostgreSQL.
+	 *
+	 * @param string $cond SQL expression which will result in a boolean value
+	 * @param string $trueVal SQL expression to return if true
+	 * @param string $falseVal SQL expression to return if false
+	 * @return string SQL fragment
+	 */
+	function conditional( $cond, $trueVal, $falseVal ) {
+		return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
+	}
 
 	# FIXME: actually detecting deadlocks might be nice
 	function wasDeadlock() {
diff --git a/maintenance/postgresql/pg_tables.sql b/maintenance/postgresql/pg_tables.sql
index 41b979ace2..5e0324e21f 100644
--- a/maintenance/postgresql/pg_tables.sql
+++ b/maintenance/postgresql/pg_tables.sql
@@ -182,8 +182,8 @@ CREATE TABLE recentchanges (
     rc_this_oldid integer NOT NULL,
     rc_last_oldid integer NOT NULL,
     rc_type smallint NOT NULL,
-    rc_moved_to_ns smallint NOT NULL,
-    rc_moved_to_title varchar NOT NULL,
+    rc_moved_to_ns smallint,
+    rc_moved_to_title varchar,
     rc_ip inet,
     rc_patrolled smallint
 );
diff --git a/maintenance/rebuildrecentchanges.inc b/maintenance/rebuildrecentchanges.inc
index 2d9fc2f072..13a8da0db4 100644
--- a/maintenance/rebuildrecentchanges.inc
+++ b/maintenance/rebuildrecentchanges.inc
@@ -17,7 +17,7 @@ function rebuildRecentChangesTablePass1()
 	$dbw->delete( 'recentchanges', '*' );
 
 	print( "Loading from CUR table...\n" );
-
+	
 	$dbw->insertSelect( 'recentchanges', 'cur', 
 		array(
 			'rc_timestamp' => 'cur_timestamp',
@@ -33,7 +33,7 @@ function rebuildRecentChangesTablePass1()
 			'rc_cur_id' => 'cur_id',
 			'rc_this_oldid' => 0,
 			'rc_last_oldid' => 0,
-			'rc_type' => 'IF(cur_is_new,' . RC_NEW . ',' . RC_EDIT . ')'
+			'rc_type' => $dbw->conditional( 'cur_is_new != 0', RC_NEW, RC_EDIT ),
 		), '*', $fname, array( 'ORDER BY' => 'inverse_timestamp', 'LIMIT' => 5000 )
 	);
 	
@@ -41,21 +41,23 @@ function rebuildRecentChangesTablePass1()
 
 	$sql = "INSERT INTO $recentchanges (rc_timestamp,rc_cur_time,rc_user," .
       "rc_user_text,rc_namespace,rc_title,rc_comment,rc_minor,rc_bot,rc_new," .
-      "rc_cur_id,rc_this_oldid,rc_last_oldid) SELECT old_timestamp,cur_timestamp," .
+      "rc_cur_id,rc_this_oldid,rc_last_oldid,rc_type) SELECT old_timestamp,cur_timestamp," .
 	  "old_user,old_user_text,old_namespace,old_title,old_comment," .
-	  "old_minor_edit,0,0,cur_id,old_id,0 FROM $old,$cur " .
+	  "old_minor_edit,0,0,cur_id,old_id,0,0 FROM $old,$cur " .
 	  "WHERE old_namespace=cur_namespace AND old_title=cur_title ORDER BY $old.inverse_timestamp " .
 	  "LIMIT 5000";
 	$dbw->query( $sql );
 
 	$sql = "SELECT rc_timestamp FROM $recentchanges " .
-	  "ORDER BY rc_timestamp DESC LIMIT 5000,1";
+	  "ORDER BY rc_timestamp DESC" . $dbw->limitResult( 1, 5000 );
 	$res = $dbw->query( $sql );
 	$obj = $dbw->fetchObject( $res );
-	$ts = $obj->rc_timestamp;
-
-	$sql = "DELETE FROM $recentchanges WHERE rc_timestamp < '{$ts}'";
-	$dbw->query( $sql );
+	if( $obj ) {
+		$ts = $obj->rc_timestamp;
+	
+		$sql = "DELETE FROM $recentchanges WHERE rc_timestamp < '{$ts}'";
+		$dbw->query( $sql );
+	}
 }
 
 function rebuildRecentChangesTablePass2()
-- 
2.20.1