Re: postgresql meltdown on PlanetMath.org

> I'm running this db on a celeron 450Mhz with 256MB RAM and a 60GB HDD
> (7200 rpm).  For the most part I have the db running "well enough."  Over
> time however, I find that performance degrades, the count(*) above is an
> example of a command that does worse over time.  It gets run once an hour
> for stats collection.  When I first migrated the db to v7.3.1 it would
> take about 5-10 seconds (which it is close to now after a VACUUM FULL) but
> after a few weeks it would take over a minute of really intense HDD
> activity.  Also of note is that when I first loaded the data it would
> cache very well with the query taking maybe taking 15 seconds if I had
> just started the db after reboot, but when it was in its "slow" state
> repeating the query didn't noticably use the disk less (nor did it take
> less time).

To speed up your COUNT(*), how about doing this:

Create a separate table to hold a single integer.

Add a trigger after insert on your table to increment the counter in the
other table
Add a trigger after delete on your table to decrement the counter in the
other table.

That way you always have an O(1) count...

Chris