Refactor test case.

src/test/regress/expected/bfv_aggregate.out

@@ -1744,6 +1744,19 @@ select count(distinct(b)), gp_segment_id from t group by gp_segment_id;
 
 set optimizer_force_multistage_agg to off;
 drop table t;
+-- test Github Issue 17028
+create table t_17028(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.
+insert into t_17028 values (1, 1), (1, null), (null, 1);
+set gp_enable_sort_distinct to on;
+select string_agg(a::text, ',' order by b), string_agg(distinct b::text, ',') from t_17028;
+ string_agg | string_agg 
+------------+------------
+ 1,1        | 1
+(1 row)
+
+reset gp_enable_sort_distinct;
 -- CLEANUP
 set client_min_messages='warning';
 drop schema bfv_aggregate cascade;

src/test/regress/expected/bfv_aggregate_optimizer.out

@@ -1739,6 +1739,19 @@ select count(distinct(b)), gp_segment_id from t group by gp_segment_id;
 
 set optimizer_force_multistage_agg to off;
 drop table t;
+-- test Github Issue 17028
+create table t_17028(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.
+insert into t_17028 values (1, 1), (1, null), (null, 1);
+set gp_enable_sort_distinct to on;
+select string_agg(a::text, ',' order by b), string_agg(distinct b::text, ',') from t_17028;
+ string_agg | string_agg 
+------------+------------
+ 1,1        | 1
+(1 row)
+
+reset gp_enable_sort_distinct;
 -- CLEANUP
 set client_min_messages='warning';
 drop schema bfv_aggregate cascade;

src/test/regress/greenplum_schedule

@@ -182,7 +182,6 @@ test: bfv_catalog bfv_index bfv_olap bfv_aggregate bfv_partition bfv_partition_p
 # NOTE: gporca_faults uses gp_fault_injector - so do not add to a parallel group
 test: gporca_faults
 
-test: aggregate_with_sort_distinct
 test: aggregate_with_groupingsets
 
 test: nested_case_null sort bb_mpph

src/test/regress/sql/bfv_aggregate.sql

@@ -1441,6 +1441,13 @@ select count(distinct(b)), gp_segment_id from t group by gp_segment_id;
 set optimizer_force_multistage_agg to off;
 drop table t;
 
+-- test Github Issue 17028
+create table t_17028(a int, b int);
+insert into t_17028 values (1, 1), (1, null), (null, 1);
+set gp_enable_sort_distinct to on;
+select string_agg(a::text, ',' order by b), string_agg(distinct b::text, ',') from t_17028;
+reset gp_enable_sort_distinct;
+
 -- CLEANUP
 set client_min_messages='warning';
 drop schema bfv_aggregate cascade;