Re: WITH RECURSIVE patches V0.1 TODO items

On Tue, May 27, 2008 at 10:10:13AM +0900, Tatsuo Ishii wrote:
> Hi,
>
> Thanks to all who respnoded to the WITH RECURSIVE patches V0.1. Here
> are TODO items so far. Lines starting with "*" are my comments and
> questions.
>
> - SEARCH clause not supported
>
>   * do we need this for 8.4?

This would be very handy.

> - CYCLE clause not supported
>
>   * do we need this for 8.4?
>
> - the number of "partition" is limited to up to 1
>
>   * do we need this for 8.4?
>
> - "non_recursive_term UNION recursive_term" is not supported.  Always
>   UNION ALL" is requried. (i.e. "non_recursive_term UNION ALL
>   recursive_term" is supported)
>
>   * do we need this for 8.4?

Probably not.

> - mutually recursive queries are not supported
>
>   * do we need this for 8.4?
>
> - mutually recursive queries are not detected
>
>   * do we need this for 8.4?
>
> - cost of Recursive Scan is always 0

This should probably be fixed, but it leads to problems like:

> - infinit recursion is not detected
>
>   * Tom suggested let query cancel and statement_timeout handle it.

Right for this case.  Is there some way to estimate this short of a
full-on materialized views implementation?  I'm guessing we'd need to
be able to cache the transitive closure of such searches.

> - only the last SELECT of UNION ALL can include self recursion name
>
> - outer joins for recursive name and tables does not work

This would be good to fix.

> - need regression tests
>
> - need docs (at least SELECT reference manual)

I started on some of that, patch attached.

Cheers,
David.
--
David Fetter <david@fetter.org> http://fetter.org/
Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
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