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Re: Friendly help for psql

From: "Greg Sabino Mullane" <greg(at)turnstep(dot)com>
To: pgsql-patches(at)postgresql(dot)org
Subject: Re: Friendly help for psql
Date: 2008-01-20 20:32:10
Message-ID: 7e47ef7f7bb21beda78e6f4fffb0aac1@biglumber.com (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
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Tom Lane opined:

> The actual argument for doing this is nothing more nor less than
> "mysql does it like that".  99% of the people who will tell you this
> is user-friendly think so because they used mysql before coming to
> postgres.

No. While the original poster may have been making a separate comparison
to MySQL, I can assure you that my impetus for doing this is not being
driven by the behavior of the mysql client. Having "help" do something
other than throw a syntax error is a very common feature in many
interactive programs, for example openssl, gdb, ftp, bash, mail,
telnet, and vim.

> That might be sufficient reason to do it; I'm not sure.  Personally
> I find it a really bad idea for psql to be usurping syntax that
> doesn't start with a backslash, but I don't suppose I'm representative
> of people who haven't absorbed the difference between psql and SQL.

Right: this is obviously aimed at people who are new to psql.

> Note that the mysql help facility covers both the mysql program and SQL
> commands (ie both \? and \h in our terminology) so the proposed patch
> is going to be seen as pretty lacking anyway by mysql-trained users.

It gets them pointed in the right direction.

> It's interesting to note that "help", "\h", and "\?" all provoke the
> same response(s) in mysql.  Perhaps a patch that had had more than two
> seconds' design effort in it would do the same in psql; though I'm not
> sure what to do to disambiguate the case with no arguments.

I'm not looking to emulate MySQL, I'm looking to do something reasonable
when a user enters "help". Output that is generated in response to a user's
action is more likely to be read than something auto-generated at the
start of the session, and they should be able to take it from there.

Alvaro suggests:

> To avoid the usage of unadorned "help" (which I don't think is going to
> ever cause conflicts with a SQL command but perhaps it's better to be
> prepared), one idea would be to respond with "please execute \help
> instead", and then \help would emit the verbose output.

Ugh. Why make people do two steps?

- --
Greg Sabino Mullane greg(at)turnstep(dot)com
PGP Key: 0x14964AC8 200801201518
http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8
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