On 13 Nov 2010, at 15:41, David Fetter <da...@fetter.org> wrote:
On Sat, Nov 13, 2010 at 02:28:35PM +0100, Yeb Havinga wrote:
On 2010-11-12 16:51, David Fetter wrote:
On Fri, Nov 12, 2010 at 10:25:51AM -0500, Tom Lane wrote:
Yeah, that's another interesting question: should we somehow force
unreferenced CTEs to be evaluated anyhow?
Yes.
After a night's sleep I'm still thinking no. Arguments:
1) the name "Common Table Expression" suggests that t must be
regarded as an expression, hence syntactically / proof theoretic and
not as a table, set of rows / model theoretic. I.e. it is not a
"Common Table".
Disagree. A table never referred to in a query still exists.
Similarly, if a normal CTE called a data-changing function but was
nevertheless not referred to, it would still run.
Actually, it wouldn't.
But if we make the behaviour of wCTEs hard(er) to predict, we are
going to have a pretty bad feature in our hands. Let's not repeat our
mistakes, please.
Regards,
Marko Tiikkaja
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