From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Mark Cave-Ayland <mark(dot)cave-ayland(at)ilande(dot)co(dot)uk> |
Cc: | pgsql-hackers(at)postgresql(dot)org, pgsql-patches(at)postgresql(dot)org |
Subject: | Re: WIP: Hierarchical Queries - stage 1 |
Date: | 2006-09-22 14:02:33 |
Message-ID: | 25922.1158933753@sss.pgh.pa.us |
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Lists: | pgsql-hackers pgsql-patches |
Mark Cave-Ayland <mark(dot)cave-ayland(at)ilande(dot)co(dot)uk> writes:
> The main problem I can see with keeping the CTEs outside the rangetable
> is that according to the source, jointree nodes must currently have
> RANGETBLREF nodes as leaf nodes; as I understand it, your suggestion of
> maintaining the CTEs separately would involve something along the lines
> of keeping a separate CTETable and creating some form of CTETBLREF node
> that could be referenced within the jointree.
No, what I'm thinking is that a *reference* to a CTE, from within the
main query's FROM list, would create a "CTERef" RTE and then you'd have
a normal RANGETBLREF node linking to that in the jointree. This solves
the problem of where do you put the alias: on the RTE. What's not clear
to me at this point is whether there can be multiple references in a
query to the same CTE --- if there can, I suspect you must have a data
structure like this.
regards, tom lane
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