Christian’s blog

Apparently the TYPO3 version we are using, doesn’t play too nice with the MySQL Master< ->Master replication.

Sometimes, something like this is going to happen:

070826  0:44:32 [ERROR] Slave: Error 'Duplicate entry '75-222419149' for key 1' on query. Default database: 't3nb'. Query: 'INSERT INTO cache_pagesection
070826  0:44:32 [ERROR] Error running query, slave SQL thread aborted. Fix the problem, and restart the slave SQL thread with "SLAVE START". We stopped at log 'dbc-mysql1.000192' position 611861372

Well, as you can see from the last line in the log, the Slave-SQL thread found a duplicate entry and thought it is smart to just turn off the thread instead of disregarding the just made entry. So from now on, both databases drift since there ain’t no replication anymore until someone kick starts the replication again (someone being me).

Anyway, I think I finally traced the fucker down, supposedly one of the problematic cases is located in t3lib/class.t3lib_tstemplate.php on line 362.

$GLOBALS['TYPO3_DB']->exec_DELETEquery('cache_pagesection', 'page_id='.intval($GLOBALS['TSFE']->id).' AND mpvar_hash='.t3lib_div::md5int($GLOBALS['TSFE']->MP));
$GLOBALS['TYPO3_DB']->exec_INSERTquery('cache_pagesection', $insertFields);

Basically what TYPO3 is doing is a DELETE and an INSERT right afterwards. But apparently, it doesn’t check whether the DELETE even succeeded. I hacked it for now, simply adding this:

-                               $GLOBALS['TYPO3_DB']->exec_INSERTquery('cache_pagesection', $insertFields);
+                               // Only insert a new cache entry with the same value, if the DELETE succeeded
+                               if ($GLOBALS['TYPO3_DB']->sql_affected_rows() == 1)
+                                       $GLOBALS['TYPO3_DB']->exec_INSERTquery('cache_pagesection', $insertFields);
+

Sadly, this looks more and more like a race-condition between the two boxes (as in the replication / UPDATE being too slow), when users visit a edited site, that hasn’t had it’s cache regenerated yet. Problem is, it ain’t just this single spot, but also the search indexing, image cache and the whole page cache. For now we switched the cluster to active/passive load balancing, till we have a chance to see if a newer TYPO3 fixes those issues.

Life Coding, Load Balancing, MySQL, PHP, TYPO3, Work

Well, the title nearly says everything .. I managed to loose my second pair of car keys, today I somehow found out that I was driving without a drivers license, so I have to go to the registration office and apply for a new one, hopefully should be done in about 4-6 weeks. Oh hell, and I have to spend about 40 € on it ..

Well, live kinda sucks if you’re oblivious. Anyway, work is giving me a ass-load of fun right now, so I’m kinda happy, though it’s Saturday evening, I’m sitting back home, just lost all my custom build Debian packages (yes, I happen to use that at work, right after SLES) and listening to Hed PE.

Life Debian, SLES10