Re: [HACKERS] WIP: long transactions on hot standby feedback replica / proof of concept

On Fri, Aug 17, 2018 at 6:41 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2018-08-17 11:35:40 -0400, Tom Lane wrote:
> > Andres Freund <andres(at)anarazel(dot)de> writes:
> > > On 2018-08-17 18:00:20 +0300, Alexander Korotkov wrote:
> > >> So, do we have any objections to committing this?
> >
> > > I think this needs more review by other senior hackers in the community.
> >
> > TBH it sounds like a horrible hack. Disable vacuum truncation?
>
> There's another patch, which I thought Alexander was referring to, that
> does something a bit smarger. On a super short skim it seems to
> introduce a separate type of AEL lock that's not replicated, by my
> reading?

Yes, that's correct. On standby read-only queries can tolerate
concurrent heap truncation. So, there is no point to replicate AEL to
standby. Previous versions of patch tries to do that by introducing
some flag. But it appears that correct way to do this is just new
non-replicated type of AEL lock.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company