When places were introduced, the schema change upgrade scripts didn't create primary key constraints on the new tables (place, edit_place, l_X_place, place_alias, etc.). Consequently, slaves that were set up before still don't have these.

This also means there is no index on the id columns, or on (edit, place) for edit_place, which might lead to performance issues, especially as the number of places in the database grows.

The missing constraints/indexes should be added at the next schema change.