Re: Window Function "Run Conditions"

On Thu, Apr 7, 2022 at 7:11 AM David Rowley <dgrowleyml(at)gmail(dot)com> wrote:

> On Thu, 7 Apr 2022 at 19:01, David Rowley <dgrowleyml(at)gmail(dot)com> wrote:
> >
> > On Thu, 7 Apr 2022 at 15:41, Zhihong Yu <zyu(at)yugabyte(dot)com> wrote:
> > > + * We must keep the original qual in place if there is
> a
> > > + * PARTITION BY clause as the top-level WindowAgg
> remains in
> > > + * pass-through mode and does nothing to filter out
> unwanted
> > > + * tuples.
> > > + */
> > > + *keep_original = false;
> > >
> > > The comment talks about keeping original qual but the assignment uses
> the value false.
> > > Maybe the comment can be rephrased so that it matches the assignment.
> >
> > Thanks. I've just removed that comment locally now. You're right, it
> > was out of date.
>
> I've attached the updated patch with the fixed comment and a few other
> comments reworded slightly.
>
> I've also pgindented the patch.
>
> Barring any objection, I'm planning to push this one in around 10 hours
> time.
>
> David
>
Hi,

+ WINDOWAGG_PASSTHROUGH_STRICT /* Pass-through plus don't store new
+ * tuples during spool */

I think the comment in code is illustrative:

+ * STRICT pass-through mode is required for the top
window
+ * when there is a PARTITION BY clause. Otherwise we
must
+ * ensure we store tuples that don't match the
+ * runcondition so they're available to WindowAggs
above.

If you think the above is too long where WINDOWAGG_PASSTHROUGH_STRICT is
defined, maybe point to the longer version so that people can find that
more easily.

Cheers