On 25 Aug 2003 at 8:44, Stephan Szabo wrote: > On Mon, 25 Aug 2003, Rhaoni Chiu Pereira wrote: > > > Hi List, > > > > As I said before, I'm not a DBA " yet" , but I'm learning ... and I > > already have a PostgreSQL running, so I have to ask some help... > > I got a SQL as folows : > > ... > > Looking at the explain: > > It's choosing lots of nested loops because it's expecting a small number > of rows to be returned at each step but in reality there are alot of rows > so that's may not really be a good choice. > > For example the scan of ftnfco00 is expected to return 295 rows but > actually returns 9339, and it looks like it's not estimating the number of > matches between the tables very well either since the real count gets up > to 240000 in a step where the estimated rows goes to 1. > > What does explain analyze give after set enable_nestloop=off;?
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In addition to that if it is getting the stats wrong, does running vacuum analyze help? If stats are updated, it should pick up proper plans, right? Bye Shridhar -- Flon's Law: There is not now, and never will be, a language in which it is the least bit difficult to write bad programs. ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend
