Re: pgbench - extend initialization phase control

Fabien COELHO <coelho@cri.ensmp.fr>

From: Fabien COELHO <coelho@cri.ensmp.fr>
To: Fujii Masao <masao.fujii@gmail.com>
Cc: btkimurayuzk <btkimurayuzk@oss.nttdata.com>, btendouan <btendouan@oss.nttdata.com>, "ibrar.ahmad@gmail.com:" <pgsql-hackers@lists.postgresql.org>
Date: 2019-11-07T09:35:31Z
Lists: pgsql-hackers

Attachments

Hello Masao-san,

>> I do not think that this is desirable. It would be a regression, and
>> allowing a no-op is not an issue in anyway.
>
> Why is that regression, you think?

Because "pgbench -I ' d'" currently works and it would cease to work after 
the patch.

> I think that's an oversight. If I'm missing something and accepting a 
> blank character as no-op in also checkInitSteps() is really necessary 
> for some reasons, which should be documented. But, if so, another 
> question is; why should only blank character be treated as no-op, in 
> checkInitSteps()?

The idea is to have one character that can be substituted to remove any 
operation.

On principle, allowing a no-op character, whatever the choice, is a good 
idea, because it means that the caller can take advantage of that if need 
be.

I think that the actual oversight is that the checkInitSteps should be 
called at the beginning of processing initialization steps rather than 
while processing -I, because currently other places modify the 
initialization string (no-vacuum, foreign key) and thus are not checked.

I agree that it should be documented.

Attached patch adds a doc and moves the check where it should be, and 
modifies a test with an explicit no-op space initialization step.

-- 
Fabien.

Commits

  1. Add query cancellation capabilities in pgbench init phase

  2. Add "G" (server-side data generation) as an initialization step in pgbench.