Re: Issue with pgstattuple on Sequences in PostgreSQL

On Monday, June 24, 2024, Ayush Vatsa <ayushvatsa1810(at)gmail(dot)com> wrote:
>
> I was recently exploring the pgstattuple code directory and found this
> piece of code: https://github.com/postgres/postgres/blob/master/contrib/
> pgstattuple/pgstattuple.c#L255-L259.
>
> It indicates that pgstattuple supports relations, toast tables,
> materialized views, and sequences.
> However, when I executed a query with a sequence, I encountered the
> following error:
>
> postgres=> CREATE SEQUENCE serial START 101;
> CREATE SEQUENCE
> postgres=> SELECT * FROM pgstattuple('serial');
> ERROR: only heap AM is supported
> postgres=>
>
> It got stuck in this if condition - https://github.com/postgres/
> postgres/blob/master/contrib/pgstattuple/pgstattuple.c#L326-L329
>
>
> How can one use pgstattuple on sequences?
>

As-is? Doesn’t look like you can. I agree it’s a documentation bug that
this is the case with a brief explanation of why - sequences do not produce
dead tuples and do not behave like real tables aside from being able to be
selected from (i.e., no SQL update/delete command).

The code should produce an explicit error for that relkind as well.

David J.