| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "David E(dot) Wheeler" <david(at)kineticode(dot)com> |
| Cc: | Marko Tiikkaja <marko(dot)tiikkaja(at)cs(dot)helsinki(dot)fi>, David Fetter <david(at)fetter(dot)org>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: wCTE behaviour |
| Date: | 2010-11-11 17:29:11 |
| Message-ID: | 17326.1289496551@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
"David E. Wheeler" <david(at)kineticode(dot)com> writes:
> I can see that, but if one can't see the result of the write, or can't determine whether or not it will be visible in advance, what's the point of writeable CTEs?
The writeable CTE returns a RETURNING set, which you can and should use
in the outer query. The thing that is being argued about here is what
you see if you look "directly" at the target table rather than making
use of RETURNING. Essentially, I'm arguing that we shouldn't promise
any particular behavior at that level, just as we don't promise that
UPDATE updates different rows in any determinate order.
regards, tom lane
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