Re: Why standby.max_connections must be higher than primary.max_connections?

>> Because the KnownAssignedXIDs and lock tables on the standby need to
>> be large enough to contain the largest snapshot and greatest number of
>> AccessExclusiveLocks that could exist on the master at any given time.
>
> Right. Initially during the development of Hot Standby, it looked like
> the "max_connections >= master's" requirement on standbys wasn't going
> to be necessary, or could be avoided. However, Simon gave up on that
> idea on pragmatic grounds here:
>
>
http://www.postgresql.org/message-id/1252002165.2889.467.camel@ebony.2ndQuadrant
>
> I'd thought about revisiting this myself, but I think that the impetus
> to do so is lessened by recent work on logical replication.
>

Hi Peter

Your information make my question be clearly.
I understand the discussions about this restriction.

Thanks.

2013/12/12 Peter Geoghegan <pg(at)heroku(dot)com>

> On Tue, Dec 10, 2013 at 1:17 PM, Robert Haas <robertmhaas(at)gmail(dot)com>
> wrote:
> > Because the KnownAssignedXIDs and lock tables on the standby need to
> > be large enough to contain the largest snapshot and greatest number of
> > AccessExclusiveLocks that could exist on the master at any given time.
>
> Right. Initially during the development of Hot Standby, it looked like
> the "max_connections >= master's" requirement on standbys wasn't going
> to be necessary, or could be avoided. However, Simon gave up on that
> idea on pragmatic grounds here:
>
>
> http://www.postgresql.org/message-id/1252002165.2889.467.camel@ebony.2ndQuadrant
>
> I'd thought about revisiting this myself, but I think that the impetus
> to do so is lessened by recent work on logical replication.
>
> --
> Peter Geoghegan
>