On Wed, 14 Mar 2018 11:28:59 -0700 Paul Jungwirth <pj@xxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > EXCLUDE USING gist (id WITH =, as_of_date WITH &&) > null), but maybe there are other primary-key duties it doesn't meet, > like defining foreign keys that reference it. I've been on-and-off The PK does provide a unique index. It may be worth adding and index on id where ( upper as_of_date = infinity ) for faster searches of current id's (assuming, of course, that there is an infinite value for upper of as_of_date). You will also need a PK if the table is used in foreign key constraints -- the other table has to ref this table's PK. -- Steven Lembark 1505 National Ave Workhorse Computing Rockford, IL 61103 lembark@xxxxxxxxxxx +1 888 359 3508