Re: misleading error message in ProcessUtilitySlow T_CreateStatsStmt

On Fri, 22 Aug 2025 at 14:46, Álvaro Herrera <alvherre@kurilemu.de> wrote:
>
> On 2025-Aug-21, Kirill Reshke wrote:
>
> > I wouldn’t say this is misleading, but " a single relation" is indeed
> > not precise enough. IMO we need a more precise term to distinguish
> > regular relation and table func.
>
> I'm not sure.  See the definition of relation in the glossary:
> https://www.postgresql.org/docs/18/glossary.html#GLOSSARY-RELATION
>
>   The generic term for all objects in a database that have a name and a
>   list of attributes defined in a specific order. Tables, sequences,
>   views, foreign tables, materialized views, composite types, and
>   indexes are all relations.
>
>   More generically, a relation is a set of tuples; for example, the
>   result of a query is also a relation.
>
>   In PostgreSQL, Class is an archaic synonym for relation.
>
> (I wonder why this says "generically" rather than "generally".  Is that
> word choice a mistake?)  Maybe in the "For example" clause we can also
> mention table functions.
>
> --
> Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/

I am sorry: I am not following. CREATE STATISTIC will work only for
single HEAP (or other AM) relations. So, for "simple regular tables"
as one can say (not tablefunc).

You say: relation is a term for both HEAP relation, tablefunc relation
and much more.
I say:  "a single relation" in the error message is not precise enough.

Where do we disagree?

Anyway, I would say correct error message here should be:

```
db=# CREATE STATISTICS alt_stat2 ON a, b FROM tftest(1);
ERROR:  cannot define statistics for relation "alt_stat2"
DETAIL:  This operation is not supported for query result.
```

--
Best regards,
Kirill Reshke