[Pkg-owncloud-commits] [owncloud] 14/36: don't update identical values

[David Prévot]

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taffit pushed a commit to branch master
in repository owncloud.

commit 4eb90cf3dc4b350864d74a3df80bebd60de1391c
Author: Jens-Christian Fischer <jens-christian.fischer at switch.ch>
Date:   Sat Apr 11 18:06:21 2015 +0200

    don't update identical values
    
    The UPDATE oc_filecache statement blindly overwrites identical data.
    Databases like Postgres that create a new row on an update
    and mark the old one as dead will suffer from the previous
    behaviour, as millions of "new" rows are created in the database.
    
    This patch changes the WHERE clause to test for identical
    values and not updating if the values in the DB are identical
    to the ones being passed.
---
 lib/private/files/cache/cache.php | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/private/files/cache/cache.php b/lib/private/files/cache/cache.php
index 7ea0032..bb36621 100644
--- a/lib/private/files/cache/cache.php
+++ b/lib/private/files/cache/cache.php
@@ -266,10 +266,16 @@ class Cache {
 		}
 
 		list($queryParts, $params) = $this->buildParts($data);
+
+		$params = array_merge($params, $params);
 		$params[] = $id;
 
-		$sql = 'UPDATE `*PREFIX*filecache` SET ' . implode(' = ?, ', $queryParts) . '=? WHERE `fileid` = ?';
+		// don't update if the data we try to set is the same as the one in the record
+		// some databases (Postgres) don't like superfluous updates
+		$sql = 'UPDATE `*PREFIX*filecache` SET ' . implode(' = ?, ', $queryParts) . '=? ' .
+			'WHERE (' . implode(' <> ? OR ', $queryParts) . ' <> ? ) AND `fileid` = ? ';
 		\OC_DB::executeAudited($sql, $params);
+
 	}
 
 	/**

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