[PATCH] Partial indicies again

Well, getting closer. Maybe I should start version numbering the patches?

Things changed in this version:

* As Tom Lane pointed out, what to do with EXTEND INDEX. I've decided to
  remove it since there is no defined syntax for it and you cannot make an
  index more restrictive with it. Since the names of indicies don't matter,
  you may as well drop the index and make a new one if you want to change
  the predicate.

  At this stage I have only removed it from the grammer because complete
  removal would require many line-by-line changes and would end up with a
  patch much larger than this one. I'd prefer to submit that as a separate
  patch after this one is completed.

* Updates to the documentation as well as comments within the code. If you
  see a spot I missed, let me know.

* Changes to the cost estimation. This is much better than before but still
  needs some refining since index_selectivity != rel_selectivity. Feedback
  welcomed.

Issues still needing to be fixed:

* Make it pg_dump-able. I've tried to extract the expression out the of
  system tables by using stringToNode and deparse_expression but it doesn't
  seem to work. I keep getting the error: "get_names_for_var: bogus
  varlevelsup 0". Anyone know what's going on? See attachment <<expr.c>>.

* VACUUM still complains about tuple count mismatch. Anyone have a good idea
  on how to deal with this?

* The regression tests need to be changed to deal with the newly added
  regression tests for these indicies.

Oh, and it appears I accidently changed the allowed syntax a bit. You used
to have to qualify each field in the partial index predicate with the name
of the relation. That's no longer required.

Everyone still alive out there?
--
Martijn van Oosterhout <kleptog@svana.org>
http://svana.org/kleptog/
> It would be nice if someone came up with a certification system that
> actually separated those who can barely regurgitate what they crammed over
> the last few weeks from those who command secret ninja networking powers.