Re: pgbench - extend initialization phase control

From: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
To: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Cc: btendouan <btendouan(at)oss(dot)nttdata(dot)com>, "ibrar(dot)ahmad(at)gmail(dot)com:" <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: pgbench - extend initialization phase control
Date: 2019-10-24 12:16:16
Message-ID: alpine.DEB.2.21.1910241109120.32142@lancre
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Hello Masao-san,

>> The benefit of controlling where begin/end actually occur is that it may
>> have an impact on performance, and it allows to check that.
> I still fail to understand the benefit of addition of () settings.
> Could you clarify what case () settings are useful for? You are
> thinking to execute all initialization SQL statements within
> single transaction, e.g., -I (dtgp), for some reasons?

Yep. Or anything else, including without (), to allow checking the
performance impact or non impact of transactions on the initialization

>>> When using ( and ) with the -I, the documentation should indicate that double
>>> quotes are required,
>> Or single quotes, or backslash, if launch from the command line. I added a
>> mention of escaping or protection in the doc in that case.
> What about using, for example, b (BEGIN) and c (COMMIT) instead
> to avoid such restriction?

It is indeed possible. Using a open/close symmetric character ( (), {},
[]) looks more pleasing and allows to see easily whether everything is
properly closed. I switched to {} which does not generate the same quoting
issue in shell.

> I think that it's better to check whehter "v" is enclosed with () or not
> at the beginning of pgbench, and report an error if it is.
> Otherwise, if -I (dtgv) is specified, pgbench reports an error after
> time-consuming data generation is performed, and of course that data
> generation is rollbacked.

Patch v5 attached added a check for v inside (), although I'm not keen on
putting it there, and uses {} instead of ().


Attachment Content-Type Size
pgbench-init-extended-5.patch text/x-diff 10.3 KB

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