Date: Fri, 16 Nov 2018 18:43:07 -0300
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Fabien COELHO <coelho@cri.ensmp.fr>
Cc: Pavel Stehule <pavel.stehule@gmail.com>,
	Tatsuo Ishii <ishii@sraoss.co.jp>, rafia.sabih@enterprisedb.com,
	Michael Paquier <michael.paquier@gmail.com>,
	Tom Lane <tgl@sss.pgh.pa.us>,
	Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>,
	Robert Haas <robertmhaas@gmail.com>,
	PostgreSQL Developers <pgsql-hackers@postgresql.org>
Subject: Re: [HACKERS] pgbench - allow to store select results into variables
Message-ID: <20181116214307.uhpir3nvwuvjftxa@alvherre.pgsql>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <alpine.DEB.2.20.1710251209330.24229@lancre>
User-Agent: NeoMutt/20180716
Precedence: bulk

On 2017-Nov-04, Fabien COELHO wrote:

> Think of one initialization followed by two appends:
> 
>   SELECT 1 AS x \cset
>   SELECT 2 \; SELECT 3 AS y \cset
>   SELECT 4 \; SELECT 5 \; SELECT 6 AS z \gset
> 
> In the end, we must have the full 6 queries
> 
>   "SELECT 1 AS x \; SELECT 2 \; SELECT 3 AS y \; SELECT 4 \; SELECT 5 \; SELECT 6 AS z"
> 
> and know that we want to set variables from queries 1, 3 and 6 and ignore
> the 3 others.

I'm not sure I understand this.  Why is the "SELECT 2" ignored?  (I can
see why the 4 and 5 are ignored: they are not processed by gset).

What exactly does \cset do?  I thought "SELECT 2 \; SELECT 3 AS y \cset"
would search for the \; and process *both* queries.

I think the doc addition should be split.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services