| From: | Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> |
|---|---|
| To: | Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>, "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com> |
| Cc: | Jeff Davis <pgsql(at)j-davis(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Proposing WITH ITERATIVE |
| Date: | 2020-04-29 11:22:43 |
| Message-ID: | cf26b533-3d82-11d6-179d-dbcb3a698e3d@2ndquadrant.com |
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| Lists: | pgsql-hackers |
On 2020-04-29 07:09, Fabien COELHO wrote:
> I'm wondering about how to use such a feature in the context of WITH query
> with several queries having different behaviors. Currently "WITH"
> introduces a named-query (like a view), "WITH RECURSIVE" introduces a mix
> of recursive and named queries, pg really sees whether each one is
> recursive or not, and "RECURSIVE" is required but could just be guessed.
Yeah the RECURSIVE vs ITERATIVE is a bit of a red herring here. As you
say, the RECURSIVE keyword doesn't specify the processing but marks the
fact that the specification of the query is recursive.
I think a syntax that would fit better within the existing framework
would be something like
WITH RECURSIVE t AS (
SELECT base case
REPLACE ALL -- instead of UNION ALL
SELECT recursive case
)
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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