Fixes a bug on not being able to drop index on a partitioned table.

Reason for the failure is that PG11 introduced a new relation kind
RELKIND_PARTITIONED_INDEX to be used for partitioned indices.

We expanded our check to cover that case.

src/backend/distributed/executor/multi_utility.c

@@ -3578,7 +3578,7 @@ InterShardDDLTaskList(Oid leftRelationId, Oid rightRelationId,
  *
  * This code is heavily borrowed from RangeVarCallbackForDropRelation() in
  * commands/tablecmds.c in Postgres source. We need this to ensure the right
- * order of locking while dealing with DROP INDEX statments. Because we are
+ * order of locking while dealing with DROP INDEX statements. Because we are
  * exclusively using this callback for INDEX processing, the PARTITION-related
  * logic from PostgreSQL's similar callback has been omitted as unneeded.
  */
@@ -3589,6 +3589,7 @@ RangeVarCallbackForDropIndex(const RangeVar *rel, Oid relOid, Oid oldRelOid, voi
 	HeapTuple	tuple;
 	struct DropRelationCallbackState *state;
 	char		relkind;
+	char		expected_relkind;
 	Form_pg_class classform;
 	LOCKMODE	heap_lockmode;
 
@@ -3619,7 +3620,21 @@ RangeVarCallbackForDropIndex(const RangeVar *rel, Oid relOid, Oid oldRelOid, voi
 		return;					/* concurrently dropped, so nothing to do */
 	classform = (Form_pg_class) GETSTRUCT(tuple);
 
-	if (classform->relkind != relkind)
+	/*
+	 * PG 11 sends relkind as partitioned index for an index
+	 * on partitioned table. It is handled the same
+	 * as regular index as far as we are concerned here.
+	 *
+	 * See tablecmds.c:RangeVarCallbackForDropRelation()
+	 */
+	expected_relkind = classform->relkind;
+
+#if PG_VERSION_NUM >= 110000
+	if (expected_relkind == RELKIND_PARTITIONED_INDEX)
+		expected_relkind = RELKIND_INDEX;
+#endif
+
+	if (expected_relkind != relkind)
 		ereport(ERROR, (errcode(ERRCODE_WRONG_OBJECT_TYPE),
 						errmsg("\"%s\" is not an index", rel->relname)));
 

src/test/regress/expected/multi_partitioning.out

@@ -569,6 +569,36 @@ SELECT tablename, indexname FROM pg_indexes WHERE tablename LIKE 'partitioning_t
  partitioning_test_default | partitioning_test_default_id_idx
 (9 rows)
 
+-- test drop
+-- indexes created on parent table can only be dropped on parent table
+-- ie using the same index name
+-- following will fail
+DROP INDEX partitioning_test_2009_id_idx;
+ERROR:  cannot drop index partitioning_test_2009_id_idx because index partitioning_index requires it
+HINT:  You can drop index partitioning_index instead.
+-- but dropping index on parent table will succeed
+DROP INDEX partitioning_index;
+-- this index was already created on partition table
+DROP INDEX partitioning_2009_index;
+-- test drop index on non-distributed, partitioned table
+CREATE TABLE non_distributed_partitioned_table(a int, b int) PARTITION BY RANGE (a);
+CREATE TABLE non_distributed_partitioned_table_1 PARTITION OF non_distributed_partitioned_table
+FOR VALUES FROM (0) TO (10);
+CREATE INDEX non_distributed_partitioned_table_index ON non_distributed_partitioned_table(a);
+-- see index is created
+SELECT tablename, indexname FROM pg_indexes WHERE tablename LIKE 'non_distributed%' ORDER BY indexname;
+              tablename              |                 indexname                 
+-------------------------------------+-------------------------------------------
+ non_distributed_partitioned_table_1 | non_distributed_partitioned_table_1_a_idx
+(1 row)
+
+-- drop the index and see it is dropped
+DROP INDEX non_distributed_partitioned_table_index;
+SELECT tablename, indexname FROM pg_indexes WHERE tablename LIKE 'non_distributed%' ORDER BY indexname;
+ tablename | indexname 
+-----------+-----------
+(0 rows)
+
 -- test add COLUMN
 -- add COLUMN to partitioned table
 ALTER TABLE partitioning_test ADD new_column int;
@@ -1701,3 +1731,9 @@ ORDER BY
 
 DROP SCHEMA partitioning_schema CASCADE;
 NOTICE:  drop cascades to table "schema-test"
+RESET SEARCH_PATH;
+DROP TABLE IF EXISTS
+	partitioning_hash_test,
+	partitioning_hash_join_test,
+	partitioning_test_failure,
+	non_distributed_partitioned_table;

src/test/regress/expected/multi_partitioning_0.out

@@ -565,6 +565,37 @@ SELECT tablename, indexname FROM pg_indexes WHERE tablename LIKE 'partitioning_t
  partitioning_test_2009 | partitioning_2009_index
 (2 rows)
 
+-- test drop
+-- indexes created on parent table can only be dropped on parent table
+-- ie using the same index name
+-- following will fail
+DROP INDEX partitioning_test_2009_id_idx;
+ERROR:  index "partitioning_test_2009_id_idx" does not exist
+-- but dropping index on parent table will succeed
+DROP INDEX partitioning_index;
+ERROR:  index "partitioning_index" does not exist
+-- this index was already created on partition table
+DROP INDEX partitioning_2009_index;
+-- test drop index on non-distributed, partitioned table
+CREATE TABLE non_distributed_partitioned_table(a int, b int) PARTITION BY RANGE (a);
+CREATE TABLE non_distributed_partitioned_table_1 PARTITION OF non_distributed_partitioned_table
+FOR VALUES FROM (0) TO (10);
+CREATE INDEX non_distributed_partitioned_table_index ON non_distributed_partitioned_table(a);
+ERROR:  cannot create index on partitioned table "non_distributed_partitioned_table"
+-- see index is created
+SELECT tablename, indexname FROM pg_indexes WHERE tablename LIKE 'non_distributed%' ORDER BY indexname;
+ tablename | indexname 
+-----------+-----------
+(0 rows)
+
+-- drop the index and see it is dropped
+DROP INDEX non_distributed_partitioned_table_index;
+ERROR:  index "non_distributed_partitioned_table_index" does not exist
+SELECT tablename, indexname FROM pg_indexes WHERE tablename LIKE 'non_distributed%' ORDER BY indexname;
+ tablename | indexname 
+-----------+-----------
+(0 rows)
+
 -- test add COLUMN
 -- add COLUMN to partitioned table
 ALTER TABLE partitioning_test ADD new_column int;
@@ -1652,3 +1683,11 @@ ORDER BY
 
 DROP SCHEMA partitioning_schema CASCADE;
 NOTICE:  drop cascades to table "schema-test"
+RESET SEARCH_PATH;
+DROP TABLE IF EXISTS
+	partitioning_hash_test,
+	partitioning_hash_join_test,
+	partitioning_test_failure,
+	non_distributed_partitioned_table;
+NOTICE:  table "partitioning_hash_test" does not exist, skipping
+NOTICE:  table "partitioning_hash_join_test" does not exist, skipping

src/test/regress/expected/multi_partitioning_1.out

@@ -541,6 +541,44 @@ SELECT tablename, indexname FROM pg_indexes WHERE tablename LIKE 'partitioning_t
 -----------+-----------
 (0 rows)
 
+-- test drop
+-- indexes created on parent table can only be dropped on parent table
+-- ie using the same index name
+-- following will fail
+DROP INDEX partitioning_test_2009_id_idx;
+ERROR:  index "partitioning_test_2009_id_idx" does not exist
+-- but dropping index on parent table will succeed
+DROP INDEX partitioning_index;
+ERROR:  index "partitioning_index" does not exist
+-- this index was already created on partition table
+DROP INDEX partitioning_2009_index;
+ERROR:  index "partitioning_2009_index" does not exist
+-- test drop index on non-distributed, partitioned table
+CREATE TABLE non_distributed_partitioned_table(a int, b int) PARTITION BY RANGE (a);
+ERROR:  syntax error at or near "PARTITION"
+LINE 1: ...E non_distributed_partitioned_table(a int, b int) PARTITION ...
+                                                             ^
+CREATE TABLE non_distributed_partitioned_table_1 PARTITION OF non_distributed_partitioned_table
+FOR VALUES FROM (0) TO (10);
+ERROR:  syntax error at or near "PARTITION"
+LINE 1: CREATE TABLE non_distributed_partitioned_table_1 PARTITION O...
+                                                         ^
+CREATE INDEX non_distributed_partitioned_table_index ON non_distributed_partitioned_table(a);
+ERROR:  relation "non_distributed_partitioned_table" does not exist
+-- see index is created
+SELECT tablename, indexname FROM pg_indexes WHERE tablename LIKE 'non_distributed%' ORDER BY indexname;
+ tablename | indexname 
+-----------+-----------
+(0 rows)
+
+-- drop the index and see it is dropped
+DROP INDEX non_distributed_partitioned_table_index;
+ERROR:  index "non_distributed_partitioned_table_index" does not exist
+SELECT tablename, indexname FROM pg_indexes WHERE tablename LIKE 'non_distributed%' ORDER BY indexname;
+ tablename | indexname 
+-----------+-----------
+(0 rows)
+
 -- test add COLUMN
 -- add COLUMN to partitioned table
 ALTER TABLE partitioning_test ADD new_column int;
@@ -1532,3 +1570,13 @@ LINE 6:     logicalrelid IN ('partitioning_schema."schema-test"'::re...
                              ^
 DROP SCHEMA partitioning_schema CASCADE;
 NOTICE:  drop cascades to table "schema-test_2009"
+RESET SEARCH_PATH;
+DROP TABLE IF EXISTS
+	partitioning_hash_test,
+	partitioning_hash_join_test,
+	partitioning_test_failure,
+	non_distributed_partitioned_table;
+NOTICE:  table "partitioning_hash_test" does not exist, skipping
+NOTICE:  table "partitioning_hash_join_test" does not exist, skipping
+NOTICE:  table "partitioning_test_failure" does not exist, skipping
+NOTICE:  table "non_distributed_partitioned_table" does not exist, skipping

src/test/regress/sql/multi_partitioning.sql

@@ -345,6 +345,31 @@ CREATE INDEX CONCURRENTLY partitioned_2010_index ON partitioning_test_2010(id);
 -- see index is created
 SELECT tablename, indexname FROM pg_indexes WHERE tablename LIKE 'partitioning_test%' ORDER BY indexname;
 
+-- test drop
+-- indexes created on parent table can only be dropped on parent table
+-- ie using the same index name
+-- following will fail
+DROP INDEX partitioning_test_2009_id_idx;
+
+-- but dropping index on parent table will succeed
+DROP INDEX partitioning_index;
+
+-- this index was already created on partition table
+DROP INDEX partitioning_2009_index;
+
+-- test drop index on non-distributed, partitioned table
+CREATE TABLE non_distributed_partitioned_table(a int, b int) PARTITION BY RANGE (a);
+CREATE TABLE non_distributed_partitioned_table_1 PARTITION OF non_distributed_partitioned_table
+FOR VALUES FROM (0) TO (10);
+CREATE INDEX non_distributed_partitioned_table_index ON non_distributed_partitioned_table(a);
+
+-- see index is created
+SELECT tablename, indexname FROM pg_indexes WHERE tablename LIKE 'non_distributed%' ORDER BY indexname;
+
+-- drop the index and see it is dropped
+DROP INDEX non_distributed_partitioned_table_index;
+SELECT tablename, indexname FROM pg_indexes WHERE tablename LIKE 'non_distributed%' ORDER BY indexname;
+
 -- test add COLUMN
 -- add COLUMN to partitioned table
 ALTER TABLE partitioning_test ADD new_column int;
@@ -1050,3 +1075,10 @@ ORDER BY
 	1,2;
 
 DROP SCHEMA partitioning_schema CASCADE;
+RESET SEARCH_PATH;
+DROP TABLE IF EXISTS
+	partitioning_hash_test,
+	partitioning_hash_join_test,
+	partitioning_test_failure,
+	non_distributed_partitioned_table;
+