Exposing quals

Folks,

I'd like to make it possible to see qualifiers from inside functions
in PostgreSQL.  For my particular case, and for dblink, it would
allow user-space code to some remove bottlenecks which make currently
make inter-DBMS communication extremely inefficient.

The current code returns one (potentially) big string with the quals
ANDed together.  I'm thinking that the new code would:

1.  Return just a pointer.

2.  Add some functions like rsinfo_get_node_tree_str() which can turn
same into (in this case, a string, but others might get tree
structures) on demand from client code.

3.  Add wrapper functions in each untrusted PL (trusted PLs shouldn't
be doing anything that needs this).

4.  Document the above.

Please find attached the patch, and thanks to Neil Conway and Korry
Douglas for the code, and to Jan Wieck for helping me hammer out the
scheme above.  Mistakes are all mine ;)

Comments?  Questions?

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

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