Basic foreign table support.

Foreign tables are a core component of SQL/MED.  This commit does
not provide a working SQL/MED infrastructure, because foreign tables
cannot yet be queried.  Support for foreign table scans will need to
be added in a future patch.  However, this patch creates the necessary
system catalog structure, syntax support, and support for ancillary
operations such as COMMENT and SECURITY LABEL.

Shigeru Hanada, heavily revised by Robert Haas

1 files changed, 92 insertions, 1 deletions

diff --git a/src/backend/commands/foreigncmds.c b/src/backend/commands/foreigncmds.c
index db5017bcac6..2774fc52ba4 100644
--- a/src/backend/commands/foreigncmds.c
+++ b/src/backend/commands/foreigncmds.c
@@ -14,6 +14,7 @@
 #include "postgres.h"
 
 #include "access/heapam.h"
+#include "access/xact.h"
 #include "access/reloptions.h"
 #include "catalog/catalog.h"
 #include "catalog/dependency.h"
@@ -21,6 +22,7 @@
 #include "catalog/objectaccess.h"
 #include "catalog/pg_foreign_data_wrapper.h"
 #include "catalog/pg_foreign_server.h"
+#include "catalog/pg_foreign_table.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_type.h"
 #include "catalog/pg_user_mapping.h"
@@ -88,7 +90,7 @@ optionListToArray(List *options)
  *
  * This is used by CREATE/ALTER of FOREIGN DATA WRAPPER/SERVER/USER MAPPING.
  */
-static Datum
+Datum
 transformGenericOptions(Oid catalogId,
 						Datum oldOptions,
 						List *options,
@@ -1158,3 +1160,92 @@ RemoveUserMappingById(Oid umId)
 
 	heap_close(rel, RowExclusiveLock);
 }
+
+/*
+ * Create a foreign table
+ * call after DefineRelation().
+ */
+void
+CreateForeignTable(CreateForeignTableStmt *stmt, Oid relid)
+{
+	Relation	ftrel;
+	Datum		ftoptions;
+	Datum		values[Natts_pg_foreign_table];
+	bool		nulls[Natts_pg_foreign_table];
+	HeapTuple	tuple;
+	Oid			ftId;
+	AclResult	aclresult;
+	ObjectAddress myself;
+	ObjectAddress referenced;
+	Oid			ownerId;
+	ForeignDataWrapper *fdw;
+	ForeignServer *server;
+
+	/*
+	 * Advance command counter to ensure the pg_attribute tuple visible; the
+	 * tuple might be updated to add constraints in previous step.
+	 */
+	CommandCounterIncrement();
+
+	/*
+	 * For now the owner cannot be specified on create. Use effective user ID.
+	 */
+	ownerId = GetUserId();
+
+	/*
+	 * Check that the foreign server exists and that we have USAGE on it. Also
+	 * get the actual FDW for option validation etc.
+	 */
+	server = GetForeignServerByName(stmt->servername, false);
+	aclresult = pg_foreign_server_aclcheck(server->serverid, ownerId, ACL_USAGE);
+	if (aclresult != ACLCHECK_OK)
+		aclcheck_error(aclresult, ACL_KIND_FOREIGN_SERVER, server->servername);
+
+	fdw = GetForeignDataWrapper(server->fdwid);
+
+	aclresult = pg_foreign_data_wrapper_aclcheck(fdw->fdwid, ownerId, ACL_USAGE);
+	if (aclresult != ACLCHECK_OK)
+		aclcheck_error(aclresult, ACL_KIND_FDW, fdw->fdwname);
+
+	/*
+	 * Insert tuple into pg_foreign_table.
+	 */
+	ftrel = heap_open(ForeignTableRelationId, RowExclusiveLock);
+
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+
+	values[Anum_pg_foreign_table_ftrelid - 1] = ObjectIdGetDatum(relid);
+	values[Anum_pg_foreign_table_ftserver - 1] = ObjectIdGetDatum(server->serverid);
+	/* Add table generic options */
+	ftoptions = transformGenericOptions(ForeignTableRelationId,
+										PointerGetDatum(NULL),
+										stmt->options,
+										fdw->fdwvalidator);
+
+	if (PointerIsValid(DatumGetPointer(ftoptions)))
+		values[Anum_pg_foreign_table_ftoptions - 1] = ftoptions;
+	else
+		nulls[Anum_pg_foreign_table_ftoptions - 1] = true;
+
+	tuple = heap_form_tuple(ftrel->rd_att, values, nulls);
+
+	/* pg_foreign_table don't have OID */
+	ftId = simple_heap_insert(ftrel, tuple);
+
+	CatalogUpdateIndexes(ftrel, tuple);
+
+	heap_freetuple(tuple);
+
+	/* Add pg_class dependency on the server */
+	myself.classId = RelationRelationId;
+	myself.objectId = relid;
+	myself.objectSubId = 0;
+
+	referenced.classId = ForeignServerRelationId;
+	referenced.objectId = server->serverid;
+	referenced.objectSubId = 0;
+	recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+
+	heap_close(ftrel, NoLock);
+}