Re: [HACKERS] lazy_update_relstats considered harmful (was Re: [PERFORM] pg_autovacuum not having enough suction ?)

2005-03-25 Thread Tom Lane
Simon Riggs <[EMAIL PROTECTED]> writes: > On Fri, 2005-03-25 at 15:22 -0500, Tom Lane wrote: >> 2. Dead tuples don't have that much influence on scan costs either, at >> least not once they are marked as known-dead. Certainly they shouldn't >> be charged at full freight. > Yes, minor additional C

Re: [HACKERS] lazy_update_relstats considered harmful (was Re: [PERFORM]

2005-03-25 Thread Simon Riggs
On Fri, 2005-03-25 at 15:22 -0500, Tom Lane wrote: > 2. Dead tuples don't have that much influence on scan costs either, at > least not once they are marked as known-dead. Certainly they shouldn't > be charged at full freight. Yes, minor additional CPU time, but the main issue is when the dead tu

Re: [HACKERS] lazy_update_relstats considered harmful (was Re: [PERFORM]

2005-03-25 Thread Matthew T. O'Connor
Tom Lane wrote: I wrote: One thing that is possibly relevant here is that in 8.0 a plain VACUUM doesn't set reltuples to the exactly correct number, but to an interpolated value that reflects our estimate of the "steady state" average between vacuums. I wonder if that code is wrong, or if it's

[HACKERS] lazy_update_relstats considered harmful (was Re: [PERFORM] pg_autovacuum not having enough suction ?)

2005-03-25 Thread Tom Lane
I wrote: > One thing that is possibly relevant here is that in 8.0 a plain VACUUM > doesn't set reltuples to the exactly correct number, but to an > interpolated value that reflects our estimate of the "steady state" > average between vacuums. I wonder if that code is wrong, or if it's > operating