| From: | Vik Fearing <vik(at)postgresfriends(dot)org> |
|---|---|
| To: | Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: SEARCH and CYCLE clauses |
| Date: | 2020-05-20 13:04:20 |
| Message-ID: | 54e533c5-09e5-7f41-9892-d4e0f7c62598@postgresfriends.org |
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On 5/20/20 1:46 PM, Peter Eisentraut wrote:
> I have implemented the SEARCH and CYCLE clauses.
YES!
> This is standard SQL syntax attached to a recursive CTE to compute a
> depth- or breadth-first ordering and cycle detection, respectively. This
> is just convenience syntax for what you can already do manually. The
> original discussion about recursive CTEs briefly mentioned these as
> something to do later but then it was never mentioned again.
>
> SQL specifies these in terms of syntactic transformations, and so that's
> how I have implemented them also, mainly in the rewriter.
I've attempted to do this several times but didn't get anywhere with it.
I'm looking forward to reviewing this.
(And maybe it will put me on the right path for implementing <unique
predicate>.)
--
Vik Fearing
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