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Re: Backslash handling in strings

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Greg Stark <gsstark(at)mit(dot)edu>,PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Backslash handling in strings
Date: 2005-05-31 14:54:25
Message-ID: 200505311454.j4VEsPm28816@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
Tom Lane wrote:
> Greg Stark <gsstark(at)mit(dot)edu> writes:
> > The only thing I'm not clear on is what exactly is the use case for E''
> > strings. That is, who do you expect to actually use them?
> 
> The case that convinced me we need to keep some sort of backslash
> capability is this: suppose you want to put a string including a tab
> into your database.  Try to do it with psql:
> 	t=> insert into foo values ('<TAB>
> Guess what: you won't get anywhere, at least not unless you disable
> readline.  So it's nice to be able to use \t.
> 
> There are related issues involving \r and \n depending on your platform.
> And this doesn't even scratch the surface of encoding-related funnies.
> 
> So there's definitely a use-case for keeping the existing backslash
> behavior, and E'string' seems like a reasonable proposal for doing that
> without conflicting with the SQL spec.
> 
> What I do not see at the moment is how we get there from here (ie,
> dropping backslashing in regular literals) without incurring tremendous
> pain --- including breaking all existing pg_dump files, introducing
> security holes and/or data corruption into many existing apps that are
> not presently broken, and probably some other ways of ruining your day.
> I'm quite unconvinced that this particular letter of the SQL spec is
> worth complying with ...

I think this is going to be like the Win32 port, where there is little
excitement from our existing users, but it is needed to grow our user
base.

I think the E'' is useful becuase it gives people a migration path for
the escapes they are already using, and the escape mechanism itself it
something useful to keep.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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