Gavin Wahl <gavinwahl@xxxxxxxxx> writes: > It'd be nice if the planner could optimize the query (1) by turning it > into (2). I understand that it might not be able to, but if it can pull > the condition up in (3), why can't it in (4)? (3) is an instance of seeing "a = b and b = c" and deducing "a = c" from that. (4) does not follow that pattern, so it's outside the realm of what the planner can deduce. In principle we could take "a = b and (b = c or b = d)" and deduce "a = c or a = d" from that, but it'd be a lot more complication for a lot less benefit than what we get from the existing logic. regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
