Re: Autovacuum Transaction Wraparound

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.klaver@aklaver.com