On Wed, 2007-11-14 at 17:46 -0500, Tom Lane wrote:
> Russell Smith <mr-russ@pws.com.au> writes:
> > It is possible that analyze is not getting the number of dead rows right?
>
> Hah, I think you are on to something. ANALYZE is telling the truth
> about how many "dead" rows it saw, but its notion of "dead" is "not good
> according to SnapshotNow". Thus, rows inserted by a not-yet-committed
> transaction would be counted as dead. So if these are background
> auto-analyzes being done in parallel with inserting transactions that
> run for awhile, seeing a few not-yet-committed rows would be
> unsurprising.
>
> I wonder if that is worth fixing? I'm not especially concerned about
> the cosmetic aspect of it, but if we mistakenly launch an autovacuum
> on the strength of an inflated estimate of dead rows, that could be
> costly.
Sounds to me like that could result in autovacuum kicking off while
doing large data loads. This sounds suspiciously like problem someone
on -novice was having - tripping over a windows autovac bug while doing
a data load
http://archives.postgresql.org/pgsql-novice/2007-11/msg00025.php
--
Brad Nicholson 416-673-4106
Database Administrator, Afilias Canada Corp.
