pgbench failed when -f option contains a char '@'

On 18/12/2020 08:22, Wang, Shenhao wrote:

Hi, hackers

pgbench use -f filename[@weight] to receive a sql script file with a weight,
but if I create a file contains char'@', like a@2.sql, specify this file without weigth,
pgbench will failed with error:
pgbench: fatal: invalid weight specification: @2.sql

This action may be unfriendly, because the char '@' is a valid character on Linux
and Windows.

I have created a patch to modify this action. The patch is attached.

This patch changes it to first check if the file "a@2.sql" exists, and
if it doesn't, only then it tries to interpret it as a weight, as
filename "a" and weight "2.sql". That stilll doesn't fix the underlying
ambiguity, though. If you have a file called "script" and "script@1",
this makes it impossible to specify "script" with weight 1, because "-f
script@1" will now always open the file "script@1".

I think we should just leave this as it is. The user can simply rename
the file.

Or maybe one change would be worthwhile here: First check if the part
after the @ contains only digits. If doesn't, then assume it's part of
the filename rather than a weight. That would fix this for cases like
"foo@1.sql", although not for "foo@1".

- Heikki

Heikki Linnakangas <hlinnaka@iki.fi> writes:

I think we should just leave this as it is. The user can simply rename
the file.

Yeah. The assumption when we defined the script-weight syntax was that
there's no particular reason to use "@" in a script file name, and
I don't see why that's a bad assumption.

Or maybe one change would be worthwhile here: First check if the part
after the @ contains only digits. If doesn't, then assume it's part of
the filename rather than a weight. That would fix this for cases like
"foo@1.sql", although not for "foo@1".

I do not like introducing ambiguity of that sort. Not being entirely
clear on which script file is going to be read seems like a recipe
for security issues.

regards, tom lane

Hello,

pgbench use -f filename[@weight] to receive a sql script file with a weight,

ISTM that I thought of this: "pgbench -f filen@me@1" does work.

sh> touch foo@bla
sh> pgbench -f foo@bla@1
pgbench: fatal: empty command list for script "foo@bla"

The documentation could point this out, though.

--
Fabien.

Hello Tom,

I think we should just leave this as it is. The user can simply rename
the file.

Yeah. The assumption when we defined the script-weight syntax was that
there's no particular reason to use "@" in a script file name, and
I don't see why that's a bad assumption.

The "parser" looks for the last @ in the argument, so the simple
workaround is to append "@1".

I suggest the attached doc update, or anything in better English.

--
Fabien.

Fabien COELHO <coelho@cri.ensmp.fr> writes:

The "parser" looks for the last @ in the argument, so the simple
workaround is to append "@1".
I suggest the attached doc update, or anything in better English.

Agreed, done.

regards, tom lane