Gerhard Wiesinger <lists@xxxxxxxxxxxxx> writes: > I know the drawbacks of an EAV design but I don't want to discuss that. I > want to discuss the major performance decrease of PostgreSQL 8.3 > (performance was ok) to PostgreSQL 8.4 (performance is NOT ok). > Any further ideas how I can track this down? > Can someone explain the difference in query plan from an optimizer point > of view? Since you haven't shown us the 8.3 plan, it's kind of hard to speculate ;-) One thing that jumped out at me was that 8.4 appears to be expecting multiple matches in each of the left-joined tables, which is why the total rowcount estimate balloons so fast. I rather imagine that you are expecting at most one match in reality, else the query isn't going to behave nicely. Is this correct? Are you *sure* you analyzed all these tables? And if that is how the data looks, where is the actual performance problem? A bad rowcount estimate isn't in itself going to kill you. FWIW, in a similar albeit toy example, I don't see any difference between the 8.3 and 8.4 plans or cost estimates. 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
