Function GetForeignTable

src/backend/foreign/foreign.c:461–525

* GetForeignTable - look up the foreign table definition by relation oid. */

 * GetForeignTable - look up the foreign table definition by relation oid.
 */
ForeignTable *
GetForeignTable(Oid relid)
{
	Form_pg_foreign_table tableform;
	ForeignTable *ft;
	HeapTuple	tp;
	Datum		datum;
	bool		isnull;

	tp = SearchSysCache1(FOREIGNTABLEREL, ObjectIdGetDatum(relid));
	if (!HeapTupleIsValid(tp))
		elog(ERROR, "cache lookup failed for foreign table %u", relid);
	tableform = (Form_pg_foreign_table) GETSTRUCT(tp);

	ft = (ForeignTable *) palloc(sizeof(ForeignTable));
	ft->relid = relid;
	ft->serverid = tableform->ftserver;

	/* Extract the ftoptions */
	datum = SysCacheGetAttr(FOREIGNTABLEREL,
							tp,
							Anum_pg_foreign_table_ftoptions,
							&isnull);
	if (isnull)
		ft->options = NIL;
	else
		ft->options = untransformRelOptions(datum);

	ReleaseSysCache(tp);

	ft->exec_location = SeparateOutMppExecute(&ft->options);

	if (ft->exec_location == FTEXECLOCATION_ALL_SEGMENTS &&
		OidIsValid(ft->serverid) &&
		Gp_role == GP_ROLE_EXECUTE)
	{
		ForeignTable *segFt;
		segFt = GetForeignTableOnSegment(relid);
		if (segFt)
		{
			ft->serverid = segFt->serverid;

			pfree(segFt);
		}
	}

	ForeignServer *server = GetForeignServer(ft->serverid);

	if (ft->exec_location == FTEXECLOCATION_NOT_DEFINED)
	{
		ft->exec_location = server->exec_location;
	}

	ft->num_segments = SeparateOutNumSegments(&ft->options);

	if (ft->num_segments <= 0)
		ft->num_segments = GetForeignTableSegNumbers(relid);