Re: Missing the point of autovacuum

[Daryl Herzmann - Sat at 12:59:03PM -0600]
> As the months have gone by, I notice many of my tables having *lots* of
> unused item pointers.  For example,

Probably not the issue here, but we had some similar issue where we had
many long-running transactions - i.e. some careless colleague entering
"begin" into his psql shell and leaving it running for some days without
entering "commit" or "rollback", plus some instances where the
applications started a transaction without closing it.

> Perhaps I shouldn't be concerned with this?  In all, I've got around 400
> GB of data on postgresql, but am not sure how much of it is old data.

I didn't count the zeroes, but autovacuum does have rules saying it will
not touch the table until some percentages of it needs to be vacuumed
off.  This is of course configurable.

> Do I need to be running old fashioned 'vacuumdb' routinely as well?  I
> guess I just don't understand why autovacuum is not automatically doing
> this for me and I have tables with so many unused item pointers.

If you have some period of the day with less activity than else, it is a
good idea running an old-fashionated vacuum as well.  The regular vacuum
process will benefit from any work done by the autovacuum.