Re: postgres_fdw: using TABLESAMPLE to collect remote sample

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Tomas Vondra <tomas.vondra@enterprisedb.com>
Cc: James Finnerty <jfinnert@amazon.com>, pgsql-hackers@lists.postgresql.org
Date: 2022-12-31T17:23:51Z
Lists: pgsql-hackers
Tomas Vondra <tomas.vondra@enterprisedb.com> writes:
> On 12/31/22 05:42, Tom Lane wrote:
>> ERROR:  TABLESAMPLE clause can only be applied to tables and materialized views
>> I think the patch avoids that, but only accidentally, because
>> reltuples will be 0 or -1 for a view.  Maybe it'd be a good
>> idea to pull back relkind along with reltuples, and check
>> that too?

> Not sure. I guess we can rely on reltuples being 0 or -1 in such cases,
> but maybe it'd be good to at least mention that in a comment? We're not
> going to use other reltuples values for views etc.

Would anyone ever point a foreign table at a sequence?  I guess it
would be a weird use-case, but it's possible, or was till now.

			regards, tom lane



Commits

  1. Check relkind before using TABLESAMPLE in postgres_fdw

  2. Fix stale comment about sample_frac adjustment