Improve updatability checking for views and foreign tables.

Extend the FDW API (which we already changed for 9.3) so that an FDW can
report whether specific foreign tables are insertable/updatable/deletable.
The default assumption continues to be that they're updatable if the
relevant executor callback function is supplied by the FDW, but finer
granularity is now possible.  As a test case, add an "updatable" option to
contrib/postgres_fdw.

This patch also fixes the information_schema views, which previously did
not think that foreign tables were ever updatable, and fixes
view_is_auto_updatable() so that a view on a foreign table can be
auto-updatable.

initdb forced due to changes in information_schema views and the functions
they rely on.  This is a bit unfortunate to do post-beta1, but if we don't
change this now then we'll have another API break for FDWs when we do
change it.

Dean Rasheed, somewhat editorialized on by Tom Lane

1 files changed, 3 insertions, 0 deletions

diff --git a/src/include/foreign/fdwapi.h b/src/include/foreign/fdwapi.h
index 485eee320f8..e8326652693 100644
--- a/src/include/foreign/fdwapi.h
+++ b/src/include/foreign/fdwapi.h
@@ -80,6 +80,8 @@ typedef TupleTableSlot *(*ExecForeignDelete_function) (EState *estate,
 typedef void (*EndForeignModify_function) (EState *estate,
 													   ResultRelInfo *rinfo);
 
+typedef int (*IsForeignRelUpdatable_function) (Relation rel);
+
 typedef void (*ExplainForeignScan_function) (ForeignScanState *node,
 													struct ExplainState *es);
 
@@ -134,6 +136,7 @@ typedef struct FdwRoutine
 	ExecForeignUpdate_function ExecForeignUpdate;
 	ExecForeignDelete_function ExecForeignDelete;
 	EndForeignModify_function EndForeignModify;
+	IsForeignRelUpdatable_function IsForeignRelUpdatable;
 
 	/* Support functions for EXPLAIN */
 	ExplainForeignScan_function ExplainForeignScan;