On Thu, May 18, 2006 at 12:38:18PM -0700, Stephen Byers wrote: > I repeated explain analyze on the query 5 times and it came up with the same plan. Yes, but did it end up with the same runtime? That's the interesting part -- the plan will almost always be identical between explain analyze runs given that you haven't done anything in between them. > You asked about index order and physical table order. In general the index > order is indeed close to the same order as the physical table order. > However, this query is likely an exception. The data is actually from a > backup server that has filled a hole for some of the time range that I'm > specifying in my query. Well, it still isn't all that far-fetched to believe that the data has lots of correlation (which helps the index scan quite a lot) that the planner isn't able to pick up. I don't know the details here, so I can't tell you how the correlation for such a query (WHERE a=foo and b between bar and baz) is estimated. Something tells me someone else might, though. :-) /* Steinar */ -- Homepage: http://www.sesse.net/
