Re: Autovacuum integration patch

Alvaro Herrera wrote:

>Hackers,
>
>Here is a first cut at autovacuum integration. Please have a look at
>it. Note that this patch automatically creates three new files:
>
>

Couple more things that I didn't think about while we were talking about
this the other day.

XID wraparound: The patch as submitted doesn't handle XID wraparound
issues. The old contrib autovacuum would do an XID wraparound check as
it's 1st operation upon connecting to a database. If XID wraparound was
looks like it's going to be a problem soon, then the whole database
would be vacuumed, eliminating the need to check specific tables.

Better logging of autovacuum activity: I think the we could use some
more detail in the debug elog statements. For example showing exactly
what autovacuum believes the threshold and current count is.

How to deal with shared relations: As an optimization, the contrib
version of autovacuum treated shared relations different than it treated
the rest when connected to any database that is not template1. That is,
when connected to a DB other than template1, autovacuum would not issue
vacuum commands. rather it would only issue analyze commands. When
autovacuum got around to connecting to template1, it would then issue
the vacuum command. The hope was that this would reducing a shared
relation from getting vacuumed n times (where n is the number of
databases in a cluster) whenever it crossed over it's threshold. I'm
not sure if this optimizaion is really important, or even exactly correct.