To: Rod Taylor <rbt@rbt.ca>
Cc: PostgreSQL Development <pgsql-hackers@postgresql.org>,
	pgsql-sql@postgresql.org
Subject: Re: Cursors and backwards scans and SCROLL 
In-reply-to: <1047243868.28251.217.camel@jester> 
References: <21621.1047242111@sss.pgh.pa.us>
	<1047243868.28251.217.camel@jester>
Comments: In-reply-to Rod Taylor <rbt@rbt.ca>
	message dated "09 Mar 2003 16:04:28 -0500"
Date: Sun, 09 Mar 2003 16:18:10 -0500
Message-ID: <25932.1047244690@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Rod Taylor <rbt@rbt.ca> writes:
> Enforcing spec seems like the least confusing mode to operate under,
> especially given it could break simply by changing the plan -- which
> happens automagically (seemingly random).

Keep in mind though that complaints about the current bugs have been
fairly infrequent, which means that most people either don't try to
fetch backwards from a cursor, or don't try to do so on complex plans.

I'm hesitant to penalize a larger group for the benefit of a smaller
one --- which is why enforcing the spec strictly doesn't really appeal
to me, even though one could argue that the larger group had it coming.
I'd prefer to be permissive about the cases that we can support at no
cost, which not-by-coincidence are the cases that have worked correctly
up to now.

			regards, tom lane