Ian Westmacott <ianw@xxxxxxxxxxxxxx> writes: > I have this query, where PG (8.1.2) prefers Merge Join over Hash Join > over Nested Loop. However, this order turns out to increase in > performance. I was hoping someone might be able to shed some light on > why PG chooses the plans in this order, and what I might do to > influence it otherwise. Thanks, Reducing random_page_cost would influence it to prefer the nestloop. However, I doubt you're ever going to get really ideal results for this query --- the estimated row counts are too far off, and the WHERE conditions are sufficiently bizarre that there's not much hope that they'd ever be much better. regards, tom lane
