> AFAICS, making them exact would not improve the planning estimates > at all, because there are too many other sources of error. We have > approximate stats already via vacuum/analyze statistics gathering. > >> > What happens if someone deletes 75% of a table? > What happens if someone imports 30 times more rows than are already in > the table? > What happens if one table is remarkably small or even empty and you are > unaware?
If you are unaware of any of the above, you'll get poorer performance. Just make sure you run ANALYZE often enough. Anyone who does a massive change in the number of rows in a table, or updates most of a table should always do an ANALYZE afterwards. Chris ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
