In article <20060929010011.GQ34238@nasby.net>,
jim@nasby.net ("Jim C. Nasby") wrote:
> 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. :(
Can the DBA just set n_distinct? Sometimes s/he just knows what the
value should be.
Then, of course, the questions becomes how to keep vacuum et al from
messing it up.
-arturo