The MediaWiki extension [[mw:Extension:UsabilityInitiative]] once contained a sub-extension called "OptIn". This sub-extension added a database table called "optin_survey".
The sub-extension was deleted in September 2010 in r73187. The database table's schema can be viewed here: https://svn.wikimedia.org/viewvc/mediawiki/trunk/extensions/UsabilityInitiative/OptIn/OptIn.sql?revision=53909&view=markup&pathrev=73186.
This database table ("optin_survey") should be dropped from all Wikimedia wiki databases.
Version: wmf-deployment
Severity: enhancement