Re: [PATCHES] WITH RECUSIVE patches 0717

On Fri, Jul 18, 2008 at 10:41:20AM +0900, Tatsuo Ishii wrote:
> > > Here is the lastest WITH RECURSIVE patches against CVS HEAD created by
> > > Yoshiyuki Asaba and minor corrections by Tatsuo Ishii.
> >
> > I tried this patch vs. CVS HEAD used my usual configure option with
> > only --with-prefix set, then tried to make, and got:
> >
> > make[3]: *** No rule to make target `parse_cte.o', needed by `objfiles.txt'. Stop.
> > make[3]: Leaving directory `/home/shackle/pgsql/src/backend/parser'
> > make[2]: *** [parser-recursive] Error 2
> > make[2]: Leaving directory `/home/shackle/pgsql/src/backend'
> > make[1]: *** [all] Error 2
> > make[1]: Leaving directory `/home/shackle/pgsql/src'
> > make: *** [all] Error 2
> >
> > Is there something missing?
>
> Oops. I forgot to include patches against newly added files. Please
> try included patches.

This now compiles.

I have a test case that hangs and smashes.

WITH t(i) AS (
SELECT * FROM generate_series(1,5)
)
SELECT
t1.i,
2*t2.i
FROM
t AS t1
JOIN
t AS t2 USING(i);

server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.

An equivalent query without RECURSIVE breaks in a different, in some
sense even more severe, way, as in it just hands out a wrong result
set:

WITH RECURSIVE t(i) AS (
VALUES(1::int)
UNION ALL
SELECT i+1 FROM t WHERE i < 5
)
SELECT
t1.i,
2*t2.i
FROM
t AS t1
JOIN
t AS t2 USING(i);

i | ?column?
---+----------
1 | 2
2 | 4
3 | 6
4 | 8
5 | 10
(5 rows)

While this case is trivial, others are not. For example, if someone
wishes to do a k-deep summary on a parts explosion n levels deep, n>k,
one way to do this would be to JOIN the k-deep part of the path
enumeration to the parts greater than k deep.

What would need to be fixed in order to make the above things work?

Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
Skype: davidfetter XMPP: david(dot)fetter(at)gmail(dot)com

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