Re: Autovacuum Transaction Wraparound

On 3/14/19 11:45 AM, Perumal Raj wrote:

Please reply to list also.
Ccing list.

> Thanks Adrian for the reply,
>
> Yes , i went through the document.
>
> My Only Worry is , Will i hit performance issue once i reach 200M
> Age(default) even i have only static table.

If is truly static then there will be no or little xids generated so
the age will not be reached or reached slowly. Otherwise the normal
autovacuuming will keep the xids under control. The caveat being an
operation or operations that generate a lot of xids faster then the
normal autovac settings can handle.

>
>
>
> On Wed, Mar 13, 2019 at 12:23 PM Adrian Klaver
> <adrian(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)com>> wrote:
>
> On 3/11/19 1:24 PM, Perumal Raj wrote:
> > Hi Adrian
> >
> > What was the full message?
> >
> >             autovacuum: VACUUM <table name >(to prevent wraparound)
> >
> > Though i am running vacuum manually (nowadays) and autovacuum is
> running
> > perfectly once its threshold reaches.
> >
> > What will happen if my DB reaches 200M transaction age again ? (
> Here my
> > understanding is no dead tuples to cleanup --- I may be missing full
> > concept , Please correct me if i am wrong) .
> >
> > What will be impact to DB ( Performance ) During Vacuum freeze ( My
> > Assumption is autovacuum will run "vacuum freeze" once DB age
> reached
> > 200M ) ?
>
> I would read this:
>
> https://www.postgresql.org/docs/9.2/routine-vacuuming.html#VACUUM-FOR-WRAPAROUND
>
> I believe it will answer most of your questions.
>
> >
> > When should i consider to increase pg_settings value with respect to
> > Autovacuum ?
> >
> > Regards,
> >
> >
>
>
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)com>
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com