Re: VACUUM ANALYZE -vs- ANALYZE on an insert-only table.

"Matt Gordon" <m.gordon@f5.com> writes:
> If I have a table that I only use for INSERTs and queries (no UPDATEs
> or DELETEs), is it enough to just run ANALYZE on the table instead of
> VACUUM ANALYZE?  In other words, is running a VACUUM on a table useful
> if all that you're doing is INSERTing into it?

It's of marginal value: it ensures that the commit status bits of the
table's rows are up-to-date, which can save work for subsequent SELECTs.

You *must* vacuum every table in your database at least once every
billion transactions to avoid transaction wraparound problems; and in
practice you probably want to do it more frequently than that to avoid
unreasonable growth of the pg_clog/ files.  But most people don't need
daily VACUUMs to meet that goal...

One caveat: do any of your inserting transactions ever fail?  If so, you
need VACUUM to clean up any dead tuples they may have inserted before
failing.

> If it matters, we're currently using Postgres 7.2.1.

You should get yourself to 7.2.4 posthaste, if not 7.3.5 or 7.4.  There
were some really nasty bugs fixed between 7.2.1 and 7.2.4.

            regards, tom lane