Prevent RF>1 on streaming replicated tables on `master_create_worker_shards`

Prior to this change, `master_create_worker_shards` command was not checking
the replication model of the target table, thus allowing RF>1 with streaming
replicated tables. With this change, `master_create_worker_shards` errors
out on the case.

src/backend/distributed/master/master_create_shards.c

@@ -97,6 +97,7 @@ CreateShardsWithRoundRobinPolicy(Oid distributedTableId, int32 shardCount,
 	uint64 hashTokenIncrement = 0;
 	List *existingShardList = NIL;
 	int64 shardIndex = 0;
+	DistTableCacheEntry *cacheEntry = DistributedTableCacheEntry(distributedTableId);
 
 	/* make sure table is hash partitioned */
 	CheckHashPartitionedTable(distributedTableId);
@@ -138,6 +139,24 @@ CreateShardsWithRoundRobinPolicy(Oid distributedTableId, int32 shardCount,
 						errmsg("replication_factor must be positive")));
 	}
 
+	/* make sure that RF=1 if the table is streaming replicated */
+	if (cacheEntry->replicationModel == REPLICATION_MODEL_STREAMING &&
+		replicationFactor > 1)
+	{
+		ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+						errmsg("using replication factor %d with streaming "
+							   "replicated tables are not supported",
+							   replicationFactor),
+						errdetail("When master_create_distributed_table is called with "
+								  "citus.replication_model streaming, then the table is "
+								  "marked for streaming replication and the shard "
+								  "replication factor of streaming replicated tables "
+								  "must be 1."),
+						errhint("Use replication factor 1 or set "
+								"citus.replication_model to streaming and recreate the "
+								"table")));
+	}
+
 	/* calculate the split of the hash space */
 	hashTokenIncrement = HASH_TOKEN_COUNT / shardCount;
 

src/test/regress/expected/multi_create_table.out

@@ -160,6 +160,26 @@ SELECT repmodel FROM pg_dist_partition WHERE logicalrelid='mx_table_test'::regcl
 (1 row)
 
 DROP TABLE mx_table_test;
+-- Show that master_create_distributed_table honors citus.replication_model GUC
+CREATE TABLE s_table(a int);
+SELECT master_create_distributed_table('s_table', 'a', 'hash');
+ master_create_distributed_table 
+---------------------------------
+ 
+(1 row)
+
+SELECT repmodel FROM pg_dist_partition WHERE logicalrelid='s_table'::regclass;
+ repmodel 
+----------
+ s
+(1 row)
+
+-- Show that master_create_worker_shards complains when RF>1 and replication model is streaming
+SELECT master_create_worker_shards('s_table', 4, 2);
+ERROR:  using replication factor 2 with streaming replicated tables are not supported
+DETAIL:  When master_create_distributed_table is called with citus.replication_model streaming, then the table is marked for streaming replication and the shard replication factor of streaming replicated tables must be 1.
+HINT:  Use replication factor 1 or set citus.replication_model to streaming and recreate the table
+DROP TABLE s_table;
 RESET citus.replication_model;
 -- Show that it is not possible to create an mx table with the old 
 -- master_create_distributed_table function

src/test/regress/sql/multi_create_table.sql

@@ -126,6 +126,16 @@ SELECT create_distributed_table('mx_table_test', 'col1');
 SELECT repmodel FROM pg_dist_partition WHERE logicalrelid='mx_table_test'::regclass;
 DROP TABLE mx_table_test;
 
+-- Show that master_create_distributed_table honors citus.replication_model GUC
+CREATE TABLE s_table(a int);
+SELECT master_create_distributed_table('s_table', 'a', 'hash');
+SELECT repmodel FROM pg_dist_partition WHERE logicalrelid='s_table'::regclass;
+
+-- Show that master_create_worker_shards complains when RF>1 and replication model is streaming
+SELECT master_create_worker_shards('s_table', 4, 2);
+
+DROP TABLE s_table;
+
 RESET citus.replication_model;
 
 -- Show that it is not possible to create an mx table with the old