We've twice tried to upgrade our MediaWiki site (www.uesp.net) running MediaWiki 1.14 to 1.19 but had the same problem each time. The basic upgrade process and resulting issue goes like: - Set wiki to read only mode. - Backup database and copy into a new database. - Upgrade the new database to 1.19 (no issues though it takes an hour). - Test 1.19 wiki (no issues seen including aggressive load testing with ab). - Switch 1.19 to "live" site. - Right away the database server begins to be overloaded with hundreds of "DELETE FROM l10n_cache WHERE lc_lang=en;" queries. Some page views get through but eventually the Apache servers fill up with connections waiting for the database server which also fills up with connections that never terminate. - Switch back the live site to 1.14. The database server has to be forced closed and restarted to restore service (the delete queries never finish). A few possible causes: - One of our extensions or custom code changes is causing an issue. Unfortunately, some of the more complex/custom extensions cannot be disabled without breaking the site. - Increased database load: Our db servers are very underused and a conservative estimate is they would work fine with a 20x load increase. A small load increase from the apparent changes between 1.14 and 1.19 shouldn't cause this level of database issue. - Our database was originally created with a very old MediaWiki (1.3 I think). While the upgrade from 1.14 to 1.19 works perhaps there are lingering issues that need the wiki database to be recreated from scratch somehow. - An issue with the MediaWiki localization db cache when used with a high traffic site. My next guess on what to try is to set "$wgCacheDirectory" to a local directory which should completely avoid using the database for any localization messages if I understand things correctly. Unfortunately, I have no way of testing if this works without running through another complete upgrade attempt. Any suggestions or ideas on what to try would be appreciated.... ------------------------ Dave Humphrey - dave(a)uesp.net Server Admin - the Unofficial Elder Scrolls Pages - www.uesp.net