Re: Lots o' I/O

On Fri, 14 Feb 2003, Stephan Szabo wrote:

> On Fri, 14 Feb 2003, Clarence Gardner wrote:
>
> >
> > I have a database that was populated about two months ago, and one
> > particular table has begun causing problems. It's got about 20,000
> > records, all fixed length of about 1 kbytes. If we do any operation
> > that involves a sequential scan of that table (e.g., select count(*)),
> > it now takes about 20 seconds, and according to linux vmstat, reads
> > 275000 disk blocks (275 mbytes). The database is vacuumed each night.
>
> What does vacuum full verbose <table> show? And how big is the actual
> data file?
>

The FULL made the difference -- the table now performs like the copy.
Despite a nightly vacuum analyze, we've never done a vacuum full. The
docs (http://www.postgresql.org/docs/view.php?version=7.3&idoc=0&file=sql-vacuum.html)
almost, but not quite, come out against it....

We're going to do a full vacuum weekly now.

Thanks, all.