On Thu, Sep 28, 2006 at 03:19:46PM -0700, Casey Duncan wrote: > I have some databases that have grown significantly over time (as > databases do). As the databases have grown, I have noticed that the > statistics have grown less and less accurate. In particular, the > n_distinct values have become many OOM too small for certain foreign > key columns. Predictably this leads to poor query plans.
Search the -hackers archives. The problem is that you can't actually get a good n_distinct estimate if you're sampling less than a very large chunk of the table. Since our sampling maxes out at something like 30k pages, at some point the n_distinct estimates just degrade. :( Patches/solutions welcome. :) -- Jim Nasby [EMAIL PROTECTED] EnterpriseDB http://enterprisedb.com 512.569.9461 (cell) ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org
