Re: What kind of locks does vacuum process hold on the db?

On 8/29/07, Nitin Verma <nitinverma@azulsystems.com> wrote:
> What kind of locks does it hold on the db? Table level / Row level /
> AccessExclusiveLock ?
> Is there a document that details vacuum process, and its internals?
>
>
> Use case: I am doing a vacuum {all full analyze} on a postgres 8.1 hosting
> two user databases. For this I am using ${pg-home}/bin/vacuumdb, not direct
> SQLs. Parallel to this I am running transaction on both user-DBs.
> Observation:
> Transactions don't pause while vacuum is running. (Odd, how come?)

Why are you doing FULL vacuums?  Is there some problem that regular
vacuums aren't solving?

> After this I tried two vacuums in parallel but those lock each other.

Yes, vacuum full takes a hard lock on a table.

Vacuum full is to be avoided.