ImportForeignSchema(ImportForeignSchemaStmt *stmt)
{
	ForeignServer *server;
	ForeignDataWrapper *fdw;
	FdwRoutine *fdw_routine;
	AclResult	aclresult;
	List	   *cmd_list;
	ListCell   *lc;

	/* Check that the foreign server exists and that we have USAGE on it */
	server = GetForeignServerByName(stmt->server_name, false);
	aclresult = pg_foreign_server_aclcheck(server->serverid, GetUserId(), ACL_USAGE);
	if (aclresult != ACLCHECK_OK)
		aclcheck_error(aclresult, OBJECT_FOREIGN_SERVER, server->servername);

	/* Check that the schema exists and we have CREATE permissions on it */
	(void) LookupCreationNamespace(stmt->local_schema);

	/* Get the FDW and check it supports IMPORT */
	fdw = GetForeignDataWrapper(server->fdwid);
	if (!OidIsValid(fdw->fdwhandler))
		ereport(ERROR,
				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
				 errmsg("foreign-data wrapper \"%s\" has no handler",
						fdw->fdwname)));
	fdw_routine = GetFdwRoutine(fdw->fdwhandler);
	if (fdw_routine->ImportForeignSchema == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_FDW_NO_SCHEMAS),
				 errmsg("foreign-data wrapper \"%s\" does not support IMPORT FOREIGN SCHEMA",
						fdw->fdwname)));

	/* Call FDW to get a list of commands */
	cmd_list = fdw_routine->ImportForeignSchema(stmt, server->serverid);

	/* Parse and execute each command */
	foreach(lc, cmd_list)
	{
		char	   *cmd = (char *) lfirst(lc);
		import_error_callback_arg callback_arg;
		ErrorContextCallback sqlerrcontext;
		List	   *raw_parsetree_list;
		ListCell   *lc2;

		/*
		 * Setup error traceback support for ereport().  This is so that any
		 * error in the generated SQL will be displayed nicely.
		 */
		callback_arg.tablename = NULL;	/* not known yet */
		callback_arg.cmd = cmd;
		sqlerrcontext.callback = import_error_callback;
		sqlerrcontext.arg = (void *) &callback_arg;
		sqlerrcontext.previous = error_context_stack;
		error_context_stack = &sqlerrcontext;

		/*
		 * Parse the SQL string into a list of raw parse trees.
		 */
		raw_parsetree_list = pg_parse_query(cmd);

		/*
		 * Process each parse tree (we allow the FDW to put more than one
		 * command per string, though this isn't really advised).
		 */
		foreach(lc2, raw_parsetree_list)
		{
			RawStmt    *rs = lfirst_node(RawStmt, lc2);
			CreateForeignTableStmt *cstmt = (CreateForeignTableStmt *) rs->stmt;
			PlannedStmt *pstmt;

			/*
			 * Because we only allow CreateForeignTableStmt, we can skip parse
			 * analysis, rewrite, and planning steps here.
			 */
			if (!IsA(cstmt, CreateForeignTableStmt))
				elog(ERROR,
					 "foreign-data wrapper \"%s\" returned incorrect statement type %d",
					 fdw->fdwname, (int) nodeTag(cstmt));

			/* Ignore commands for tables excluded by filter options */
			if (!IsImportableForeignTable(cstmt->base.relation->relname, stmt))
				continue;

			/* Enable reporting of current table's name on error */
			callback_arg.tablename = cstmt->base.relation->relname;

			/* Ensure creation schema is the one given in IMPORT statement */
			cstmt->base.relation->schemaname = pstrdup(stmt->local_schema);

			/* No planning needed, just make a wrapper PlannedStmt */
			pstmt = makeNode(PlannedStmt);
			pstmt->commandType = CMD_UTILITY;
			pstmt->canSetTag = false;
			pstmt->utilityStmt = (Node *) cstmt;
			pstmt->stmt_location = rs->stmt_location;
			pstmt->stmt_len = rs->stmt_len;

			/* Execute statement */
			ProcessUtility(pstmt,
						   cmd,
						   PROCESS_UTILITY_SUBCOMMAND, NULL, NULL,
						   None_Receiver, NULL);

			/* Be sure to advance the command counter between subcommands */
			CommandCounterIncrement();

			callback_arg.tablename = NULL;
		}

		error_context_stack = sqlerrcontext.previous;
	}
}
ImportForeignSchema(ImportForeignSchemaStmt *stmt)
{
	ForeignServer *server;
	ForeignDataWrapper *fdw;
	FdwRoutine *fdw_routine;
	AclResult	aclresult;
	List	   *cmd_list;
	ListCell   *lc;

	 
	server = GetForeignServerByName(stmt->server_name, false);
	aclresult = pg_foreign_server_aclcheck(server->serverid, GetUserId(), ACL_USAGE);
	if (aclresult != ACLCHECK_OK)
		aclcheck_error(aclresult, OBJECT_FOREIGN_SERVER, server->servername);

	 
	(void) LookupCreationNamespace(stmt->local_schema);

	 
	fdw = GetForeignDataWrapper(server->fdwid);
	if (!OidIsValid(fdw->fdwhandler))
		ereport(ERROR,
				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
				 errmsg("foreign-data wrapper \"%s\" has no handler",
						fdw->fdwname)));
	fdw_routine = GetFdwRoutine(fdw->fdwhandler);
	if (fdw_routine->ImportForeignSchema == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_FDW_NO_SCHEMAS),
				 errmsg("foreign-data wrapper \"%s\" does not support IMPORT FOREIGN SCHEMA",
						fdw->fdwname)));

	 
	cmd_list = fdw_routine->ImportForeignSchema(stmt, server->serverid);

	 
	foreach(lc, cmd_list)
	{
		char	   *cmd = (char *) lfirst(lc);
		import_error_callback_arg callback_arg;
		ErrorContextCallback sqlerrcontext;
		List	   *raw_parsetree_list;
		ListCell   *lc2;

		 
		callback_arg.tablename = NULL;	 
		callback_arg.cmd = cmd;
		sqlerrcontext.callback = import_error_callback;
		sqlerrcontext.arg = (void *) &callback_arg;
		sqlerrcontext.previous = error_context_stack;
		error_context_stack = &sqlerrcontext;

		 
		raw_parsetree_list = pg_parse_query(cmd);

		 
		foreach(lc2, raw_parsetree_list)
		{
			RawStmt    *rs = lfirst_node(RawStmt, lc2);
			CreateForeignTableStmt *cstmt = (CreateForeignTableStmt *) rs->stmt;
			PlannedStmt *pstmt;

			 
			if (!IsA(cstmt, CreateForeignTableStmt))
				elog(ERROR,
					 "foreign-data wrapper \"%s\" returned incorrect statement type %d",
					 fdw->fdwname, (int) nodeTag(cstmt));

			 
			if (!IsImportableForeignTable(cstmt->base.relation->relname, stmt))
				continue;

			 
			callback_arg.tablename = cstmt->base.relation->relname;

			 
			cstmt->base.relation->schemaname = pstrdup(stmt->local_schema);

			 
			pstmt = makeNode(PlannedStmt);
			pstmt->commandType = CMD_UTILITY;
			pstmt->canSetTag = false;
			pstmt->utilityStmt = (Node *) cstmt;
			pstmt->stmt_location = rs->stmt_location;
			pstmt->stmt_len = rs->stmt_len;

			 
			ProcessUtility(pstmt,
						   cmd,
						   PROCESS_UTILITY_SUBCOMMAND, NULL, NULL,
						   None_Receiver, NULL);

			 
			CommandCounterIncrement();

			callback_arg.tablename = NULL;
		}

		error_context_stack = sqlerrcontext.previous;
	}
}