Re: Status report on writeable CTEs

On Sat, Jul 17, 2010 at 01:15:22AM +0900, Hitoshi Harada wrote:
> 2010/7/17 Marko Tiikkaja <marko.tiikkaja@cs.helsinki.fi>:
> > On 7/16/10 6:15 PM +0300, Hitoshi Harada wrote:
> >>
> >> 1. Use MaterialNode instead of adding DtScanNode. Since MaterialNode
> >> is exsiting one that work with single tuplestore, it might be sane to
> >> modify this so that it accepts tuplestore from Query instead of its
> >> child node.
> >
> > I thought about this, but I don't necessarily like the idea of overloading
> > executor nodes.
> 
> Neither do I have good shape for this solution. Maybe it's not good
> idea. But my concern is adding DtScanNode, which looks similar to
> MaterialNode. Of course each purpose is different, but quite big part
> will overlap each other, I think.

Any ideas as to how to factor this out?  Handiest ideas would be in
the form of a patch ;)

> >> 2. Use temp table instead of tuplestore list. Since we agreed we need
> >> to execute each plan one by one starting and shutting down executor,
> >> it now looks very simple strategy.
> >
> > I didn't look at this because I thought using a "tuplestore receiver" in the
> > portal logic was simple enough.  Any thoughts on how this would work?
> 
> It's just deconstructing queries like:
> 
> WITH t AS (INSERT INTO x ... RETURING *)
> SELECT * FROM t;
> 
> to
> 
> CREATE TEMP TABLE t AS INSERT INTO x ... RETURING *;
> SELECT * FROM t;
> 
> While the second statement is not implemented yet, it will be so simpler.

So CTAS would get expanded into CTA[row-returning query] ?
Interesting.  How much work would that part be?

Cheers,
David.
-- 
David Fetter <david@fetter.org> http://fetter.org/
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