gpreload failed - Reason='error 'ERROR: more than one row returned by a subquery used as an expression

Products

• VMware Tanzu Greenplum

Issue/Introduction

In Greenplum, specifically versions below 6.11, if you have multiple objects with the same name, gpreload will fail with the following message:

20200720:15:18:59:028814 gpreload:dcwipphpgp007:gpadmin-[CRITICAL]:-gpreload failed. 
(Reason='error 'ERROR: more than one row returned by a subquery used as an expression ' in 'SELECT attname FROM pg_attribute 
WHERE attrelid = (SELECT pg_class.oid FROM pg_class, pg_namespace 
WHERE pg_class.relname = 'vehicle_revenue_f' 
AND pg_namespace.nspname = 'sales')'') exiting... 

Here is how to reproduce the error:

gpadmin=# create table sales (a int, b int); 
NOTICE: Table doesn't have 'DISTRIBUTED BY' clause 
-- Using column named 'a' as the Greenplum Database data distribution 
key for this table. HINT: The 'DISTRIBUTED BY' clause determines 
the distribution of data. Make sure column(s) chosen are 
the optimal data distribution key to minimize skew. 
CREATE TABLE 
gpadmin=# create schema test; 
CREATE SCHEMA 
gpadmin=# create view test.sales as select * from sales; 
CREATE VIEW 
gpadmin=# \q 
[gpadmin@gpdb2-m tmp]$ cat gpreload public.sales: a, b 
[gpadmin@gpdb2-m tmp]$ gpreload -d gpadmin -t gpreload 
20200730:18:33:19:016880 gpreload:gpdb2-m:gpadmin-[
INFO]:-Starting gpreload with args: -d gpadmin -t gpreload 20200730:18:33:19:016880 gpreload:gpdb2-m:gpadmin-
[INFO]:-Validating table file gpreload 20200730:18:33:19:016880 
gpreload:gpdb2-m:gpadmin-[INFO]:-Obtaining parent partitions 20200730:18:33:19:016880 gpreload:gpdb2-m:gpadmin-
[INFO]:-Validating tables 20200730:18:33:19:016880 gpreload:gpdb2-m:gpadmin-[CRITICAL]:-gpreload failed. 
(Reason='error 'ERROR: more than one row returned by a subquery used as an expression ' in 'SELECT attname FROM pg_attribute 
WHERE attrelid = (SELECT pg_class.oid FROM pg_class, pg_namespace 
WHERE pg_class.relname = 'sales' AND pg_namespace.nspname = 'public')'') exiting...

Environment

Product Version: 6.7

Resolution

Upgrade to 6.11, there are no other workarounds.