Re: should INSERT SELECT use a BulkInsertState?

On Sat, Sep 19, 2020 at 08:32:15AM -0500, Justin Pryzby wrote:
> On Sun, Jul 12, 2020 at 08:57:00PM -0500, Justin Pryzby wrote:
> > On Thu, Jun 04, 2020 at 10:30:47AM -0700, Andres Freund wrote:
> > > On 2020-05-08 02:25:45 -0500, Justin Pryzby wrote:
> > > > Seems to me it should, at least conditionally. At least if there's a function
> > > > scan or a relation or ..
> > >
> > > Well, the problem is that this can cause very very significant
> > > regressions. As in 10x slower or more. The ringbuffer can cause constant
> > > XLogFlush() calls (due to the lsn interlock), and the eviction from
> > > shared_buffers (regardless of actual available) will mean future vacuums
> > > etc will be much slower. I think this is likely to cause pretty
> > > widespread regressions on upgrades.
> > >
> > > Now, it sucks that we have this problem in the general facility that's
> > > supposed to be used for this kind of bulk operation. But I don't really
> > > see it realistic as expanding use of bulk insert strategies unless we
> > > have some more fundamental fixes.
> >
> > I made this conditional on BEGIN BULK/SET bulk, so I'll solicit comments on that.
>
> @cfbot: rebased

again

--
Justin