On Sat, Nov 13, 2010 at 03:23:42PM +0100, Yeb Havinga wrote:
> On 2010-11-13 14:41, David Fetter wrote:
> >On Sat, Nov 13, 2010 at 02:28:35PM +0100, Yeb Havinga wrote:
> >>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.
> with t as (select nextval('seq'))
> select 1;
>
> does not update the sequence.
I think you've found a bug in the form of an over-aggressive
optimization for the data-changing case.
Cheers,
David.
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