unreferenced saved searches (place: uris) are never removed from places.sqlite this might actually be by design. from http://mxr.mozilla.org/mozilla/source/toolkit/components/places/src/nsNavHistoryExpire.cpp#530 530 // We need to be careful not to delete bookmarks, place:URIs and 531 // URIs with EXPIRE_NEVER annotations. But, I can't remember why we don't delete place: URIs if there is no moz_bookmark that is associated with it. the way I came across this bug was to create a saved search for "foo". then I changed it from "foo" to "bar", and then again from "bar" to "baz". I had one bookmark in moz_bookmarks with a fk that pointed back to the place: query for "baz", but the previous place: uris for "foo" and "bar" still remained. dietrich / mano, do you remember why we do this?

something to add to preventive maintenance once it lands.

this was fixed when we moved to async expiration