Re: Defaults for replication/backup - Mailing list pgsql-hackers

From Magnus Hagander
Subject Re: Defaults for replication/backup
Date
Msg-id CABUevEyoMGjn=9E5hG4Pp4krVw7QF+YVZj31weTq6ih5Z1K6-A@mail.gmail.com
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In response to Re: Defaults for replication/backup  (Andres Freund <andres@anarazel.de>)
Responses Re: Defaults for replication/backup
List pgsql-hackers


On Sat, Feb 13, 2016 at 2:39 PM, Andres Freund <andres@anarazel.de> wrote:
On 2016-02-13 22:37:33 +0900, Michael Paquier wrote:
> On Sat, Feb 13, 2016 at 10:15 PM, Magnus Hagander wrote:
> > So, I suggest the following changes to the defaults:
> > wal_level=hot_standby
> > max_wal_senders=10
> > max_replication_slots=10

+1. I'm inclined to set slots a bit higher than senders. They're pretty
cheap...

So something like 10/20?

 
I think this is way past due.

> 10 seems a bit high. I would think that max_wal_senders and
> max_replication_slots set at 3 are sufficient enough, giving enough
> room for simple deployments willing to use replication.

But they're relatively cheap to enable, so why set them low?


That's my reasoning as well. I think you will be hard pressed to even measure the overhead between 3 and 10. The big difference will be in leaving 0 and in particular setting wal_level. 

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