Re: Incremental View Maintenance, take 2

On Mon, 28 Aug 2023 11:52:52 +0900
Yugo NAGATA <nagata(at)sraoss(dot)co(dot)jp> wrote:

> On Mon, 28 Aug 2023 02:49:08 +0900
> Yugo NAGATA <nagata(at)sraoss(dot)co(dot)jp> wrote:
>
> > On Sun, 2 Jul 2023 10:38:20 +0800
> > jian he <jian(dot)universality(at)gmail(dot)com> wrote:
>
> I attahed the patches v29 updated to comments from jian he.
> The changes from the previous includes:
>
> - errors in documentations is fixed.
> - remove unnecessary BEGIN from the test
> - add isimmv column to pg_matviews system view
> - fix a typo
> - rebase to the master branch

I found pg_dump test was broken, so attached the fixed version.

Regards,
Yugo Nagata

>
> >
> > > ok. Now I really found a small bug.
> > >
> > > this works as intended:
> > > BEGIN;
> > > CREATE INCREMENTAL MATERIALIZED VIEW test_ivm AS SELECT i, MIN(j) as
> > > min_j FROM mv_base_a group by 1;
> > > INSERT INTO mv_base_a select 1,-2 where false;
> > > rollback;
> > >
> > > however the following one:
> > > BEGIN;
> > > CREATE INCREMENTAL MATERIALIZED VIEW test_ivm1 AS SELECT MIN(j) as
> > > min_j FROM mv_base_a;
> > > INSERT INTO mv_base_a select 1, -2 where false;
> > > rollback;
> > >
> > > will evaluate
> > > tuplestore_tuple_count(new_tuplestores) to 1, it will walk through
> > > IVM_immediate_maintenance function to apply_delta.
> > > but should it be zero?
> >
> > This is not a bug because an aggregate without GROUP BY always
> > results one row whose value is NULL.
> >
> > The contents of test_imv1 would be always same as " SELECT MIN(j) as min_j
> > FROM mv_base_a;", isn't it?
> >
> >
> > Regards,
> > Yugo Nagata
> >
> > --
> > Yugo NAGATA <nagata(at)sraoss(dot)co(dot)jp>
> >
> >
>
>
> --
> Yugo NAGATA <nagata(at)sraoss(dot)co(dot)jp>

--
Yugo NAGATA <nagata(at)sraoss(dot)co(dot)jp>