Horton

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

Fabien COELHO <coelho@cri.ensmp.fr>

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From: Fabien COELHO <coelho@cri.ensmp.fr>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Michael Paquier <michael@paquier.xyz>, Stephen Frost <sfrost@snowman.net>, Andrew Dunstan <andrew.dunstan@2ndquadrant.com>, PostgreSQL Developers <pgsql-hackers@postgresql.org>
Date: 2018-11-18T10:23:08Z
Lists: pgsql-hackers

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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.
>
> [...]

Ok.

>>> 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.

-- 
Fabien.

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.