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@momjian.us>        https://momjian.us
  EnterpriseDB                             https://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +