Re: Vacuum Full

On Tue, Mar 31, 2009 at 10:04 AM, Rafael Domiciano
<rafael(dot)domiciano(at)gmail(dot)com> wrote:
> Hello People,
>
> I have some doubts about Vacuum Full. There We go:
> 1) The Only thing that Vacuum Full (Only Full, not Analyze) is to clean
> "dead space" on the disc, and reorganize the relation at the physical level?
> If it's true, so doing this may speed up select's, while the Postgres will
> going to do less hit in the disc. I'm right?

Generally speaking, vacuum full should not normally be needed.
Regular vacuuming should free up enough free space that the table
reaches an equilibrium where it has some small percentage of available
space (5 to 15% or so) and stay there.

> 2) Doing only Vacuum Analyze I have a enlargement of the parameter
> max_fsm_pages. Does it have any impact in the operation?
> Should I increment the value in the conf to be so large than the Vacuum
> Verbose shows me?

If the needed fsm settings need to keep increasing then something is wrong.

> 3) There are differences in performace of Vacuum Full between versions 8.1.4
> and 8.3.7?
> As soon as possible we are going to migrate the Postgres to 8.3.7, just
> waiting the finish of the tests of the software in the new version.

Yeah, 8.3 is faster.

> 4) The right way to run Vacuum and Reindex is: Vacuum and Reindex or Reindex
> and Vacuum?
> Running Vacuum I have a Index Bloat, right?! So I have to run Reindex afet
> Vacuum?!
> If true I'll change the script to make first Vacuum and then Reindex.

yep, vacuum full, then reindex.

> 5) Does have any way to see how much is left to finish vacuum?

Not that I know of.

I notice you don't mention autovacuum. Are you running it? And if
not, why not?