Re: SQL/MED - FDW API

Attached are rebased version of patches for FDW API.

To make review easier, I split core functionality into 3 patches.
Please apply these patches in the following order.

1) fdw_handler - this patch adds HANDLER option to both syntax and
catalog of FOREIGN DATA WRAPPER.

2) foreign_scan - this patch adds following: ForeignScan executor-node,
hooks in planner and executor, and FdwRoutine (FDW API).

3) fdw_catalog_lookup - this patch adds GetForeignTable() whicch
returns ForeignTable object, similar to GetForeignDataWrapper(),
GetForeignServer(), and GetUserMapping(). This function is assumed to
be used by FDWs.

You would be able to test these patches with "20110114" version of file_fdw
wrapper patches which will be posted in another thread.

Regards,
--
Shigeru Hanada