Re: Avoiding pin scan during btree vacuum

Andres Freund <andres@anarazel.de> writes:
> On 2016-01-03 15:40:01 +0000, Simon Riggs wrote:
>> I'm happy with this being a simple patch now, not least because I would
>> like to backpatch this to 9.4 where catalog scans became MVCC.
>> 
>> A backpatch is warranted because it is a severe performance issue with
>> replication and we can fix that before 9.5 hits the streets.
>> 
>> I'll be doing some more testing and checking, so not in a rush.

> This seems like a might subtle thing to backpatch. If we really want to
> go there, ISTM that the relevant code should stew in an unreleased
> branch for a while, before being backpatched.

I'm definitely -1 on back-patching such a thing.  Put it in HEAD for
awhile.  If it survives six months or so then we could discuss it again.
        regards, tom lane