Implemented save/restore logic for sql_big_selects, per CR comments on r50168.

includes/LogEventsList.php

@@ -745,14 +745,10 @@ class LogPager extends ReverseChronologicalPager {
 	}
 
 	public function doQuery() {
-		// Work around MySQL optimizer bug
-		if ( in_array( get_class( $this->mDb ), array( 'Database', 'DatabaseMysql' ) ) ) {
-			$this->mDb->query( 'SET SQL_BIG_SELECTS=1' );
-			parent::doQuery();
-			$this->mDb->query( 'SET SQL_BIG_SELECTS=0' );
-		} else {
-			parent::doQuery();
-		}
+		// Workaround MySQL optimizer bug
+		$this->mDb->setBigSelects();
+		parent::doQuery();
+		$this->mDb->setBigSelects( 'default' );
 	}
 }
 

includes/db/Database.php

@@ -39,6 +39,7 @@ class Database {
 	protected $mErrorCount = 0;
 	protected $mLBInfo = array();
 	protected $mFakeSlaveLag = null, $mFakeMaster = false;
+	protected $mDefaultBigSelects = null;
 
 #------------------------------------------------------------------------------
 # Accessors
@@ -2393,6 +2394,29 @@ class Database {
 	public function getSearchEngine() {
 		return "SearchMySQL";
 	}
+
+	/**
+	 * Allow or deny "big selects" for this session only. This is done by setting 
+	 * the sql_big_selects session variable.
+	 *
+	 * This is a MySQL-specific feature. 
+	 *
+	 * @param mixed $value true for allow, false for deny, or "default" to restore the initial value
+	 */
+	public function setBigSelects( $value = true ) {
+		if ( $value === 'default' ) {
+			if ( $this->mDefaultBigSelects === null ) {
+				# Function hasn't been called before so it must already be set to the default
+				return;
+			} else {
+				$value = $this->mDefaultBigSelects;
+			}
+		} elseif ( $this->mDefaultBigSelects === null ) {
+			$this->mDefaultBigSelects = (bool)$this->selectField( false, '@@sql_big_selects' );
+		}
+		$encValue = $value ? '1' : '0';
+		$this->query( "SET sql_big_selects=$encValue", __METHOD__ );
+	}
 }
 
 /**

includes/db/DatabaseIbm_db2.php

@@ -1792,5 +1792,8 @@ SQL;
 		// TODO
 		// see SpecialAncientpages
 	}
+
+	/** No-op */
+	public function setBigSelects( $value = true ) {}
 }
-?>
+?>

includes/db/DatabaseMssql.php

@@ -1015,6 +1015,8 @@ class DatabaseMssql extends Database {
 		return "SearchEngineDummy";
 	}
 
+	/** No-op */
+	public function setBigSelects( $value = true ) {}
 }
 
 /**

includes/db/DatabaseOracle.php

@@ -721,4 +721,7 @@ echo "error!\n";
 		return "SearchOracle";
 	}
 
+	/** No-op */
+	public function setBigSelects( $value = true ) {}
+
 } // end DatabaseOracle class

includes/db/DatabasePostgres.php

@@ -1438,4 +1438,7 @@ END;
 		return "SearchPostgres";
 	}
 
+	/** No-op */
+	public function setBigSelects( $value = true ) {}
+
 } // end DatabasePostgres class

includes/db/DatabaseSqlite.php

@@ -497,6 +497,9 @@ class DatabaseSqlite extends Database {
 		return $s;
 	}
 
+	/** No-op */
+	public function setBigSelects( $value = true ) {}
+
 } // end DatabaseSqlite class
 
 /**