Re: tablesample with partitioned tables

From: David Fetter <david(at)fetter(dot)org>
To: Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
Cc: Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: tablesample with partitioned tables
Date: 2017-02-22 15:54:04
Message-ID: 20170222155404.GA18866@fetter.org
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On Wed, Feb 22, 2017 at 04:51:46PM +0900, Amit Langote wrote:
> Attached patch fixes an oversight that tablesample cannot be used with
> partitioned tables:
>
> create table p (a int) partition by list (a);
> select * from p tablesample bernoulli (50);
> ERROR: TABLESAMPLE clause can only be applied to tables and materialized
> views

Thanks!

Should the error message change somehow to reflect that partitioned
tables are included? Is complete transparency of partitioned tables
the goal, and reasonable in this context?

Also, is there a good reason apart from tuits not to expand
TABLESAMPLE to the rest of our SQL-visible relation structures? I'm
guessing this could have something to do with the volatility they
might have, whether in views that call volatile functions or in
foreign tables that might not make the right guarantees...

Best,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
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