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

From: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
To: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
Cc: Michael Paquier <michael(at)paquier(dot)xyz>, Stephen Frost <sfrost(at)snowman(dot)net>, Andrew Dunstan <andrew(dot)dunstan(at)2ndquadrant(dot)com>, PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [HACKERS] pgbench - allow to store select results into variables
Date: 2018-11-18 10:23:08
Message-ID: alpine.DEB.2.21.1811180851210.19159@lancre
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Hello Alvaro,

>>> I think this patch's Command->lines would benefit from using PQExpBuffer
>>> (or maybe StringInfo?) for the command string instead of open-coding
>>> string manipulation and allocation.
> [...]


>>> I'm not sure that Command->first_line is really all that useful. It
>>> seems we go to a lot of trouble to keep it up to date. Isn't it easier
>>> to chop Command->lines at the first newline when it is needed?
>> Hmmm, it is needed quite often (about 12 times) to report errors, that would
>> mean having to handle the truncation in many places, so I felt it was worth
>> the trouble.
> Ok, as long as we don't repeat the work during script execution.

Sure, the point of first_line is that it is computed once at parse time.

Attached a v23 with PQExpBuffer for managing lines.

I've also added a function to compute the summary first line, which
handles carriage-return.


Attachment Content-Type Size
pgbench-into-23.patch text/x-diff 27.6 KB

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