Re: Review: query result history in psql

>
> It's better to post a review as a reply to the message which contains
> the patch.

Sorry about that, I did not have the email in my inbox and couldn't figure
out how to use the old message ID to send a reply. Here is the thread:
http://www.postgresql.org/message-id/flat/CAEcSYXJRi++T3pevDyzAWH2yGx7kG9ZrhX8KAWtP1fXV3H02vw(at)mail(dot)gmail(dot)com#CAEcSYXJRi++T3pevDyzAWH2yGx7kG9ZrhX8KAWtP1fXV3H02vw@mail.gmail.com

The 'EscapeForCopy' was meant to mean 'Escape string in a format require by
> the COPY TEXT format', so 'copy' in the name refers to the escaping format,
> not the action performed by the function.
>

I see, that makes sense now. Keep it as you see fit, it's not a big deal in
my opinion.

Some mathematical toolkits, like Matlab or Mathematica, automatically set
> a variable called 'ans' (short for "answer") containing the result of the
> last operation. I was trying to emulate exactly this behaviour.

I've actually been using Matlab lately, which must be why the name made
sense to me intuitively. I don't know if this is the best name, however. It
kind of assumes that our users use Matlab/Octave/Mathematica. Maybe 'qhist'
or 'hist' or something?

The history is not erased. The history is always stored in the client's
> memory.

Ah, I did not pick up on that. Thank you for explaining it! That's actually
a very neat way of doing it. Sorry I did not realize that at first.

I was considering such a behaviour. But since the feature is turned off by
> default, I decided that whoever is using it, is aware of cost. Instead of
> truncating the history automatically (which could lead to a nasty
> surprise), I decided to equip the user with \ansclean , a command erasing
> the history. I believe that it is better to let the user decide when
> history should be erased, instead of doing it automatically.

I think you are correct. However, if we turn on the feature by default (at
some point in the future) the discussion should probably be re-visited.

This is my first submitted patch, so I can't really comment on the
> process. But if you could add the author's email to CC, the message would
> be much easier to spot. I replied after two days only because I missed the
> message in the flood of other pgsql-hacker messages. I think I need to scan
> the list more carefully...

My fault, I definitely should have CC'd you.

As for the patch, I made a new version of the latest one you provided in
the original thread. Let me know if anything breaks, but it compiles fine
on my box. Thanks for the feedback!

Ian