>In many cases, using bit encoding to try and squeeze a bit of efficiency is the wrong tactic, better to have a set of binary fields that you can build indexes on if you really want to be able to select on things like this efficiently I do it for *process* efficiency, not runtime. Schema changes are significant events (for non-technical reasons) whereas using a previously reserved bit is a trivial non-event. Using INTEGER as a logical BOOLEAN[64] avoids these non-technical issues. There's also some runtime efficiency but that's not as significant to me.