Re: pgbench - add \aset to store results of a combined query

From: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
To: Michael Paquier <michael(at)paquier(dot)xyz>
Cc: Ibrar Ahmed <ibrar(dot)ahmad(at)gmail(dot)com>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: pgbench - add \aset to store results of a combined query
Date: 2019-11-29 09:34:05
Message-ID: alpine.DEB.2.21.1911291013490.12886@pseudo
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Michaël,

> + bool aset;
>
> It seems to me that there is no point to have the variable aset in
> Command because this structure includes already MetaCommand, so the
> information is duplicated. [...] Perhaps I am missing something?

Yep. ISTM that you are missing that aset is not an independent meta
command like most others but really changes the state of the previous SQL
command, so that it needs to be stored into that with some additional
fields. This is the same with "gset" which is tagged by a non-null
"varprefix".

So I cannot remove the "aset" field.

> And I would suggest to change readCommandResponse() to use a MetaCommand
> in argument.

MetaCommand is not enough: we need varprefix, and then distinguishing
between aset and gset. Although this last point can be done with a
MetaCommand, ISTM that a bool is_aset is clear and good enough. It is
possible to switch if you insist on it, but I do not think it is
desirable.

Attached v4 removes an unwanted rebased comment duplication and does minor
changes while re-reading the code.

--
Fabien.

Attachment Content-Type Size
pgbench-aset-4.patch text/x-diff 9.8 KB

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