Horton

Re: [HACKERS] pgbench - allow to store select results into variables

Alvaro Herrera <alvherre@2ndquadrant.com>

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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>
Date: 2018-11-16T21:43:07Z
Lists: pgsql-hackers 
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

Commits

  1. pgbench: Remove \cset

  2. pgbench: add \cset and \gset commands

  3. Adjust pgbench to allow non-ASCII characters in variable names.

  4. Refactor script execution state machine in pgbench.

  5. Allow empty queries in pgbench.