silverstripe/silverstripe-framework — pull request #2267 by jthomerson (2013-07-25 23:36:53+00:00)
Title: FIX: using ->subtract breaks Translatable

Using $allList->subtract($gridField->getList()) breaks Translatable->augmentSQL because
it finds the Locale filter in the subquery and assumes it does not need to augment the
actual search query. When you have a very large table with many records not in the
locale that you are searching, this can affect the search time by several orders of
magnitude.