Re: Improving connection scalability: GetSnapshotData()

On Wed, Apr 8, 2020 at 03:25:34PM -0700, Andres Freund wrote:
> Hi,
>
> On 2020-04-08 18:06:23 -0400, Bruce Momjian wrote:
> > If we don't commit this, where does this leave us with the
> > old_snapshot_threshold feature? We remove it in back branches and have
> > no working version in PG 13? That seems kind of bad.
>
> I don't think this patch changes the situation for
> old_snapshot_threshold in a meaningful way.
>
> Sure, this patch makes old_snapshot_threshold scale better, and triggers
> fewer unnecessary query cancellations. But there still are wrong query
> results, the tests still don't test anything meaningful, and the
> determination of which query is cancelled is still wrong.

Oh, OK, so it still needs to be disabled. I was hoping we could paint
this as a fix.

Based on Robert's analysis of the risk (no SQL syntax, no storage
changes), I think, if you are willing to keep working at this until the
final release, it is reasonable to apply it.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EnterpriseDB https://enterprisedb.com

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