Thread

Re: per-column generic option

Shigeru Hanada <shigeru.hanada@gmail.com> — 2011-06-27T14:47:51Z

(2011/06/26 18:34), Kohei KaiGai wrote:
> I checked your patch.

Thanks for the review!  Please find attached a revised patch.

> The backend portion seems to me OK, but I have several questions/comments.
> 
> * This patch should be rebased.
> It conflicts with the latest bin/psql/describe.c and
> include/catalog/catversion.h.
> IIRC, we should not touch catversion.h in submission stage. (It might
> be a task of
> committer when a patch get upstreamed.)

I've rebased against current HEAD, and reverted catversion.h.

> * It might be an option to extend attreloptions, instead of the new
> attfdwoptions.
> Although I didn't track the discussion when pg_foreign_table catalog
> that provides
> relation level fdw-options, was it impossible or unreasonable to extend existing
> design of reloptions/attoptions?
> Right now, it accepts only hard-wired options listed at reloptions.c.
> But, it seems
> to me worthwhile, if it could accept options validated by loadable modules.

IIRC someone has objected against storing FDW options in
reloptions/attoptions, but I couldn't find such post.  I'll follow the
discussion again.

IMHO, though at present I don't have clear proof, separating FDW options
from access method options seems better than merging them, but  I should
learn more about AM mechanism to clarify this issue.  Please check other
issues first.

> * pg_dump shall die when we run it for older postgresql version.
> 
> This patch does not modify queries to older postgresql version at
> getTableAttrs().
> In the result, this index shall be set by -1.
> +       i_attfdwoptions = PQfnumber(res, "attfdwoptions");
> 
> Then, PGgetvalue() returns NULL for unranged column number, and strdup()
> shall cause segmentation fault.
> +           tbinfo->attfdwoptions[j] = strdup(PQgetvalue(res, j,
> i_attfdwoptions));
> 
> In fact, I tried to run the patched pg_dump towards v9.0.2
>    [kaigai@vmlinux pg_dump]$ ./pg_dump postgres
>    pg_dump: column number -1 is out of range 0..14
>    Segmentation fault
> 
> My recommendation is to append "NULL as attfdwoptions" on the queries to
> older versions. It eventually makes PGgetvalue() to return an empty string,
> then strdup() does not cause a problem.

Fixed in the way you've recommended, and tested against 8.4.  I should
have noticed that same technique is used in some other places...

BTW, I also have found an unnecessary FIXME comment and removed it.
Please see the line 2845 of src/backend/catalog/heap.c
(InsertPgAttributeTuple) for the correction.

Regards,
-- 
Shigeru Hanada