-- CURRENTLY USED
SELECT a.uid AS uid FROM tx_extensionmanager_domain_model_extension a WHERE integer_version=(SELECT MAX(integer_version) FROM tx_extensionmanager_domain_model_extension b WHERE b.repository = 1 AND a.extension_key = b.extension_key) AND repository = 1;
-- 6411 rows in set(1.72 sec)

-- CHANGED QUERY
SELECT uid FROM tx_extensionmanager_domain_model_extension a WHERE repository = 1 GROUP BY extension_key HAVING MAX(integer_version);
-- 6381 rows in set (0.09 sec)