more

src/backend/distributed/operations/create_shards.c

@@ -54,6 +54,9 @@
 #include "distributed/transaction_management.h"
 #include "distributed/worker_manager.h"
 
+/* Config variables managed via guc */
+bool EnableSingleShardTableMultiNodePlacement = false;
+
 
 /* declarations for dynamic loading */
 PG_FUNCTION_INFO_V1(master_create_worker_shards);
@@ -165,7 +168,8 @@ CreateShardsWithRoundRobinPolicy(Oid distributedTableId, int32 shardCount,
 	char shardStorageType = ShardStorageType(distributedTableId);
 
 	int64 shardOffset = 0;
-	if (shardCount == 1 && shardStorageType == SHARD_STORAGE_TABLE)
+	if (EnableSingleShardTableMultiNodePlacement && shardCount == 1
+		&& shardStorageType == SHARD_STORAGE_TABLE)
 	{
 		/* For single shard distributed tables, use the colocationId to offset
 		 * where the shard is placed.

src/backend/distributed/shared_library_init.c

@@ -86,6 +86,7 @@
 #include "distributed/multi_router_planner.h"
 #include "distributed/multi_server_executor.h"
 #include "distributed/pg_dist_partition.h"
+#include "distributed/pg_dist_shard.h"
 #include "distributed/placement_connection.h"
 #include "distributed/priority.h"
 #include "distributed/query_pushdown_planning.h"
@@ -1462,6 +1463,17 @@ RegisterCitusConfigVariables(void)
 		GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE,
 		NULL, NULL, NULL);
 
+	DefineCustomBoolVariable(
+		"citus.enable_single_shard_table_multi_node_placement",
+		gettext_noop("Enables placement of single shard distributed tables in"
+					 " all nodes of the cluster"),
+		NULL,
+		&EnableSingleShardTableMultiNodePlacement,
+		false,
+		PGC_USERSET,
+		GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE,
+		NULL, NULL, NULL);
+
 	DefineCustomBoolVariable(
 		"citus.enable_statistics_collection",
 		gettext_noop("Enables sending basic usage statistics to Citus."),

src/include/distributed/pg_dist_shard.h

@@ -59,5 +59,6 @@ typedef FormData_pg_dist_shard *Form_pg_dist_shard;
 #define SHARD_STORAGE_TABLE 't'
 #define SHARD_STORAGE_VIRTUAL 'v'
 
+extern bool EnableSingleShardTableMultiNodePlacement;
 
 #endif   /* PG_DIST_SHARD_H */

src/test/regress/expected/multi_create_table.out

@@ -468,6 +468,7 @@ DROP TABLE temp_table;
 DROP TABLE shard_count_table_3;
 -- test shard count 1 placement with colocate none.
 -- create a base table instance
+set citus.enable_single_hash_repartition_joins to on;
 CREATE TABLE shard_count_table_1_inst_1 (a int);
 SELECT create_distributed_table('shard_count_table_1_inst_1', 'a', shard_count:=1, colocate_with:='none');
  create_distributed_table

src/test/regress/sql/multi_create_table.sql

@@ -294,6 +294,7 @@ DROP TABLE shard_count_table_3;
 
 -- test shard count 1 placement with colocate none.
 -- create a base table instance
+set citus.enable_single_hash_repartition_joins to on;
 CREATE TABLE shard_count_table_1_inst_1 (a int);
 SELECT create_distributed_table('shard_count_table_1_inst_1', 'a', shard_count:=1, colocate_with:='none');