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
Subject: Re: postgres_fdw: using TABLESAMPLE to collect remote sample
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Comments: In-reply-to Tomas Vondra <tomas.vondra@enterprisedb.com>
	message dated "Sat, 31 Dec 2022 00:03:08 +0100"
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Date: Fri, 30 Dec 2022 23:42:24 -0500
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Tomas Vondra <tomas.vondra@enterprisedb.com> writes:
> After thinking about it a bit more I decided to rip out the 10% sampling
> rate inflation.

+1.  I'm not sure if there's anything more we need to do there, but
that didn't seem like that was it.

I notice that the committed patch still has a reference to that hack
though:

+            * Ensure the sampling rate is between 0.0 and 1.0, even after=
 the
+            * 10% adjustment above.  (Clamping to 0.0 is just paranoia.)

Clamping still seems like a wise idea, but the comment is just
confusing now.

Also, I wonder if there is any possibility of ANALYZE failing
with

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?

			regards, tom lane