Re: DDL Partitionion Inheritance -- improved trigger function

On Tue, Sep 23, 2025, 16:30 David Rowley <dgrowleyml(at)gmail(dot)com> wrote:

> On Wed, 24 Sept 2025 at 04:25, Kirk Parker <khp(at)equatoria(dot)us> wrote:
> > I'm a big fan of maintenance-free functions. What would you think about
> adding the following as an alternative trigger function, or as a
> replacement for the current function, to
> >
> https://www.postgresql.org/docs/current/ddl-partitioning.html#DDL-PARTITIONING-INHERITANCE-EXAMPLE
> , item #5?
> >
> > CREATE OR REPLACE FUNCTION measurement_insert_trigger()
> > RETURNS TRIGGER AS $$
> > BEGIN
> > EXECUTE format('INSERT INTO measurement_%s VALUES (NEW.*)', to_char(
> NEW.logdate, 'YYYYMM'));
> > RETURN NULL;
> > END;
> > $$
> > LANGUAGE plpgsql;
>
> I've somewhat mixed feelings about that. While I do agree that it
> might be a good way to code things to help prevent a DBA from a
> midnight callout, I'm just not sure I'm that onboard with adding the
> example. About 10 years ago, I'd likely just have agreed, but since
> then we've got declarative partitioning and the legitimate use cases
> for using inheritance partitioning over the newer method are very
> limited. Today when I look at that page in the documents, I wonder how
> we could write less about inheritance partitioning or if we could move
> the inheritance section out into another page rather than having it
> mixed up with the declarative partitioning sections, perhaps headed up
> with a note to redirect people to the declarative partitioning
> section. I fear adding your proposed example might increase the
> chances of someone landing on that section if they're skimming the
> page.
>
> Overall, I'm about -0.01 on your idea. I might be in favour of it if
> the inheritance section had a dedicated page.
>
> David
>

I get what you're saying. My email sat in my drafts folder for a couple
days while I was debating whether to send it or not, for the exact reason
that inheritance-based partitioning is, with a few exceptions, a legacy
concept.

One way to "write less about inheritance partitioning", though, would be to
present the suggested new function as the only example of the trigger
function. That would shorten the section by replacing the two current
functions along with some of the surrounding explanatory verbiage.

Possible patch attached; this is my first ever submission so I hope I
didn't miss anything.