Re: EXPLAIN/EXPLAIN ANALYZE REFRESH MATERIALIZED VIEW

On Mon, Dec 28, 2020 at 5:56 PM Bharath Rupireddy
<bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
>
> On Tue, Dec 22, 2020 at 7:01 PM Bharath Rupireddy
> <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
> > Currently, $subject is not allowed. We do plan the mat view query
> > before every refresh. I propose to show the explain/explain analyze of
> > the select part of the mat view in case of Refresh Mat View(RMV). It
> > will be useful for the user to know what exactly is being planned and
> > executed as part of RMV. Please note that we already have
> > explain/explain analyze CTAS/Create Mat View(CMV), where we show the
> > explain/explain analyze of the select part. This proposal will do the
> > same thing.
> >
> > The behaviour can be like this:
> > EXPLAIN REFRESH MATERIALIZED VIEW mv1; --> will not refresh the mat
> > view, but shows the select part's plan of mat view.
> > EXPLAIN ANALYZE REFRESH MATERIALIZED VIEW mv1; --> will refresh the
> > mat view and shows the select part's plan of mat view.
> >
> > Thoughts? If okay, I will post a patch later.
>
> Attaching below patches:
>
> 0001 - Rearrange Refresh Mat View Code - Currently, the function
> ExecRefreshMatView in matview.c is having many lines of code which is
> not at all good from readability and maintainability perspectives.
> This patch adds a few functions and moves the code from
> ExecRefreshMatView to them making the code look better.
>
> 0002 - EXPLAIN/EXPLAIN ANALYZE REFRESH MATERIALIZED VIEW support and tests.
>
> If this proposal is useful, I have few open points - 1) In the patch I
> have added a new mat view info parameter to ExplainOneQuery(), do we
> also need to add it to ExplainOneQuery_hook_type? 2) Do we document
> (under respective command pages or somewhere else) that we allow
> explain/explain analyze for a command?
>
> Thoughts?

Attaching v2 patch set reabsed on the latest master f7a1a805cb. And
also added an entry for upcoming commitfest -
https://commitfest.postgresql.org/32/2928/

Please consider the v2 patches for further review.

With Regards,
Bharath Rupireddy.
EnterpriseDB: http://www.enterprisedb.com