Fix: check and ereport error in external table

In external table with CFTYPE_EXEC. We check and ereport
error when external_getnext return null.

Author: lss602726449

gpcontrib/gp_exttable_fdw/extaccess.c

@@ -491,6 +491,27 @@ external_getnext_init(PlanState *state)
 	return desc;
 }
 
+static void
+check_error(FileScanDesc scan)
+{
+	char   *relname = RelationGetRelationName(scan->fs_rd);
+	int		ebuflen = 512;
+	char	ebuf[512];
+
+	ebuf[0] = '\0';
+	/* current only CFTYPE_EXEC will read stderr to ebuf */
+	if (url_ferror(scan->fs_file, -1, ebuf, ebuflen))
+	{
+		if (*ebuf && strlen(ebuf) > 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_EXTERNAL_ROUTINE_EXCEPTION),
+					 errmsg("external table %s command ended with error. %s",
+							(relname ? relname : ""), ebuf),
+					 errdetail("Command: %s", scan->fs_file->url)));
+	}
+
+}
+
 /* ----------------------------------------------------------------
 *		external_getnext
 *
@@ -530,6 +551,8 @@ external_getnext(FileScanDesc scan, ScanDirection direction, ExternalSelectDesc
 	{
 		FILEDEBUG_2;			/* external_getnext returning EOS */
 
+		check_error(scan);
+
 		return NULL;
 	}
 

src/test/regress/input/external_table.source

@@ -3700,3 +3700,6 @@ SELECT logerrors, options from pg_exttable a, pg_class b where a.reloid = b.oid
 DROP EXTERNAL TABLE ext_false;
 DROP EXTERNAL TABLE ext_true;
 DROP EXTERNAL TABLE ext_persistently;
+
+CREATE EXTERNAL WEB TEMP TABLE test_program_not_exist(content text) EXECUTE '/xx/seq 1 5' ON MASTER FORMAT 'TEXT';
+SELECT * FROM test_program_not_exist;

src/test/regress/output/external_table.source

@@ -5052,3 +5052,7 @@ SELECT logerrors, options from pg_exttable a, pg_class b where a.reloid = b.oid
 DROP EXTERNAL TABLE ext_false;
 DROP EXTERNAL TABLE ext_true;
 DROP EXTERNAL TABLE ext_persistently;
+CREATE EXTERNAL WEB TEMP TABLE test_program_not_exist(content text) EXECUTE '/xx/seq 1 5' ON MASTER FORMAT 'TEXT';
+SELECT * FROM test_program_not_exist;
+DETAIL:  Command: execute:/xx/seq 1 5
+ERROR:  external table test_program_not_exist command ended with error. sh: line 1: /xx/seq: No such file or directory

src/test/regress/output/external_table_optimizer.source

@@ -5054,3 +5054,7 @@ SELECT logerrors, options from pg_exttable a, pg_class b where a.reloid = b.oid
 DROP EXTERNAL TABLE ext_false;
 DROP EXTERNAL TABLE ext_true;
 DROP EXTERNAL TABLE ext_persistently;
+CREATE EXTERNAL WEB TEMP TABLE test_program_not_exist(content text) EXECUTE '/xx/seq 1 5' ON MASTER FORMAT 'TEXT';
+SELECT * FROM test_program_not_exist;
+DETAIL:  Command: execute:/xx/seq 1 5
+ERROR:  external table test_program_not_exist command ended with error. sh: line 1: /xx/seq: No such file or directory