Merge pull request #1137 from citusdata/make_rep_model_explicit

Add replication_model GUC

cr: @anarazel

src/backend/distributed/commands/create_distributed_table.c

@@ -60,11 +60,14 @@
 #include "utils/inval.h"
 
 
+/* Replication model to use when creating distributed tables */
+int ReplicationModel = REPLICATION_MODEL_COORDINATOR;
+
+
 /* local function forward declarations */
 static void CreateReferenceTable(Oid relationId);
 static void ConvertToDistributedTable(Oid relationId, char *distributionColumnName,
-									  char distributionMethod, uint32 colocationId,
+									  char distributionMethod, uint32 colocationId);
-									  char replicationModel);
 static char LookupDistributionMethod(Oid distributionMethodOid);
 static Oid SupportFunctionForColumn(Var *partitionColumn, Oid accessMethodId,
 									int16 supportFunctionNumber);
@@ -106,8 +109,7 @@ master_create_distributed_table(PG_FUNCTION_ARGS)
 	EnsureSchemaNode();
 
 	ConvertToDistributedTable(distributedRelationId, distributionColumnName,
-							  distributionMethod, INVALID_COLOCATION_ID,
+							  distributionMethod, INVALID_COLOCATION_ID);
-							  REPLICATION_MODEL_COORDINATOR);
 
 	PG_RETURN_VOID();
 }
@@ -164,8 +166,7 @@ create_distributed_table(PG_FUNCTION_ARGS)
 	if (distributionMethod != DISTRIBUTE_BY_HASH)
 	{
 		ConvertToDistributedTable(relationId, distributionColumnName,
-								  distributionMethod, INVALID_COLOCATION_ID,
+								  distributionMethod, INVALID_COLOCATION_ID);
-								  REPLICATION_MODEL_COORDINATOR);
 		PG_RETURN_VOID();
 	}
 
@@ -228,7 +229,7 @@ CreateReferenceTable(Oid relationId)
 
 	/* first, convert the relation into distributed relation */
 	ConvertToDistributedTable(relationId, distributionColumnName,
-							  DISTRIBUTE_BY_NONE, colocationId, REPLICATION_MODEL_2PC);
+							  DISTRIBUTE_BY_NONE, colocationId);
 
 	/* now, create the single shard replicated to all nodes */
 	CreateReferenceTableShard(relationId);
@@ -250,14 +251,27 @@ CreateReferenceTable(Oid relationId)
  */
 static void
 ConvertToDistributedTable(Oid relationId, char *distributionColumnName,
-						  char distributionMethod, uint32 colocationId,
+						  char distributionMethod, uint32 colocationId)
-						  char replicationModel)
 {
 	Relation relation = NULL;
 	TupleDesc relationDesc = NULL;
 	char *relationName = NULL;
 	char relationKind = 0;
 	Var *distributionColumn = NULL;
+	char replicationModel = REPLICATION_MODEL_INVALID;
+
+	/* check global replication settings before continuing */
+	EnsureReplicationSettings(InvalidOid);
+
+	/* distribute by none tables use 2PC replication; otherwise use GUC setting */
+	if (distributionMethod == DISTRIBUTE_BY_NONE)
+	{
+		replicationModel = REPLICATION_MODEL_2PC;
+	}
+	else
+	{
+		replicationModel = ReplicationModel;
+	}
 
 	/*
 	 * Lock target relation with an exclusive lock - there's no way to make
@@ -891,21 +905,10 @@ CreateHashDistributedTable(Oid relationId, char *distributionColumnName,
 	uint32 colocationId = INVALID_COLOCATION_ID;
 	Oid sourceRelationId = InvalidOid;
 	Oid distributionColumnType = InvalidOid;
-	char replicationModel = 0;
 
 	/* get an access lock on the relation to prevent DROP TABLE and ALTER TABLE */
 	distributedRelation = relation_open(relationId, AccessShareLock);
 
-	/* all hash-distributed tables with repfactor=1 are treated as MX tables */
-	if (replicationFactor == 1)
-	{
-		replicationModel = REPLICATION_MODEL_STREAMING;
-	}
-	else
-	{
-		replicationModel = REPLICATION_MODEL_COORDINATOR;
-	}
-
 	/*
 	 * Get an exclusive lock on the colocation system catalog. Therefore, we
 	 * can be sure that there will no modifications on the colocation table
@@ -946,7 +949,7 @@ CreateHashDistributedTable(Oid relationId, char *distributionColumnName,
 
 	/* create distributed table metadata */
 	ConvertToDistributedTable(relationId, distributionColumnName, DISTRIBUTE_BY_HASH,
-							  colocationId, replicationModel);
+							  colocationId);
 
 	/* create shards */
 	if (sourceRelationId != InvalidOid)
@@ -979,3 +982,34 @@ ColumnType(Oid relationId, char *columnName)
 
 	return columnType;
 }
+
+
+/*
+ * Check that the current replication factor setting is compatible with the
+ * replication model of relationId, if valid. If InvalidOid, check that the
+ * global replication model setting instead. Errors out if an invalid state
+ * is detected.
+ */
+void
+EnsureReplicationSettings(Oid relationId)
+{
+	char replicationModel = (char) ReplicationModel;
+	char *msgSuffix = "the streaming replication model";
+	char *extraHint = " or setting \"citus.replication_model\" to \"statement\"";
+
+	if (relationId != InvalidOid)
+	{
+		replicationModel = TableReplicationModel(relationId);
+		msgSuffix = "tables which use the streaming replication model";
+		extraHint = "";
+	}
+
+	if (replicationModel == REPLICATION_MODEL_STREAMING && ShardReplicationFactor != 1)
+	{
+		ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+						errmsg("replication factors above one are incompatible with %s",
+							   msgSuffix),
+						errhint("Try again after reducing \"citus.shard_replication_"
+								"factor\" to one%s.", extraHint)));
+	}
+}

src/backend/distributed/master/master_create_shards.c

@@ -27,6 +27,7 @@
 #include "catalog/namespace.h"
 #include "catalog/pg_class.h"
 #include "distributed/listutils.h"
+#include "distributed/master_metadata_utility.h"
 #include "distributed/master_protocol.h"
 #include "distributed/metadata_cache.h"
 #include "distributed/multi_join_order.h"

src/backend/distributed/master/master_stage_protocol.c

@@ -127,6 +127,8 @@ master_create_empty_shard(PG_FUNCTION_ARGS)
 								  "on reference tables")));
 	}
 
+	EnsureReplicationSettings(relationId);
+
 	/* generate new and unique shardId from sequence */
 	shardId = GetNextShardId();
 

src/backend/distributed/planner/multi_join_order.c

@@ -1586,3 +1586,16 @@ PartitionMethod(Oid relationId)
 
 	return partitionMethod;
 }
+
+
+/* Returns the replication model for the given relation. */
+char
+TableReplicationModel(Oid relationId)
+{
+	/* errors out if not a distributed table */
+	DistTableCacheEntry *partitionEntry = DistributedTableCacheEntry(relationId);
+
+	char replicationModel = partitionEntry->replicationModel;
+
+	return replicationModel;
+}

src/backend/distributed/shared_library_init.c

@@ -21,6 +21,7 @@
 #include "distributed/citus_nodefuncs.h"
 #include "distributed/connection_management.h"
 #include "distributed/connection_management.h"
+#include "distributed/master_metadata_utility.h"
 #include "distributed/master_protocol.h"
 #include "distributed/multi_copy.h"
 #include "distributed/multi_executor.h"
@@ -32,6 +33,7 @@
 #include "distributed/multi_router_planner.h"
 #include "distributed/multi_server_executor.h"
 #include "distributed/multi_utility.h"
+#include "distributed/pg_dist_partition.h"
 #include "distributed/placement_connection.h"
 #include "distributed/remote_commands.h"
 #include "distributed/task_tracker.h"
@@ -63,6 +65,12 @@ static const struct config_enum_entry task_assignment_policy_options[] = {
 	{ NULL, 0, false }
 };
 
+static const struct config_enum_entry replication_model_options[] = {
+	{ "statement", REPLICATION_MODEL_COORDINATOR, false },
+	{ "streaming", REPLICATION_MODEL_STREAMING, false },
+	{ NULL, 0, false }
+};
+
 static const struct config_enum_entry task_executor_type_options[] = {
 	{ "real-time", MULTI_EXECUTOR_REAL_TIME, false },
 	{ "task-tracker", MULTI_EXECUTOR_TASK_TRACKER, false },
@@ -571,6 +579,20 @@ RegisterCitusConfigVariables(void)
 		0,
 		NULL, NULL, NULL);
 
+	DefineCustomEnumVariable(
+		"citus.replication_model",
+		gettext_noop("Sets the replication model to be used for distributed tables."),
+		gettext_noop("Depending upon the execution environment, statement- or streaming-"
+					 "based replication modes may be employed. Though most Citus deploy-"
+					 "ments will simply use statement replication, hosted and MX-style"
+					 "deployments should set this parameter to 'streaming'."),
+		&ReplicationModel,
+		REPLICATION_MODEL_COORDINATOR,
+		replication_model_options,
+		PGC_SUSET,
+		GUC_SUPERUSER_ONLY,
+		NULL, NULL, NULL);
+
 	DefineCustomEnumVariable(
 		"citus.task_executor_type",
 		gettext_noop("Sets the executor type to be used for distributed queries."),

src/include/distributed/master_metadata_utility.h

@@ -59,6 +59,9 @@ typedef struct ShardPlacement
 } ShardPlacement;
 
 
+/* Config variable managed via guc.c */
+extern int ReplicationModel;
+
 /* Function declarations to read shard and shard placement data */
 extern uint32 TableShardReplicationFactor(Oid relationId);
 extern List * LoadShardIntervalList(Oid relationId);
@@ -97,6 +100,7 @@ extern char * TableOwner(Oid relationId);
 extern void EnsureTablePermissions(Oid relationId, AclMode mode);
 extern void EnsureTableOwner(Oid relationId);
 extern void EnsureSuperUser(void);
+extern void EnsureReplicationSettings(Oid relationId);
 extern bool TableReferenced(Oid relationId);
 extern char * ConstructQualifiedShardName(ShardInterval *shardInterval);
 extern Datum StringToDatum(char *inputString, Oid dataType);

src/include/distributed/multi_join_order.h

@@ -92,6 +92,7 @@ extern Var * RightColumn(OpExpr *joinClause);
 extern Var * PartitionColumn(Oid relationId, uint32 rangeTableId);
 extern Var * PartitionKey(Oid relationId);
 extern char PartitionMethod(Oid relationId);
+extern char TableReplicationModel(Oid relationId);
 
 
 #endif   /* MULTI_JOIN_ORDER_H */

src/test/regress/expected/multi_create_table.out

@@ -137,10 +137,16 @@ SELECT master_create_distributed_table('supplier_single_shard', 's_suppkey', 'ap
  
 (1 row)
 
--- Show that when a hash distributed table with replication factor=1 is created, it 
--- automatically marked as streaming replicated
-SET citus.shard_replication_factor TO 1;
 CREATE TABLE mx_table_test (col1 int, col2 text);
+-- Since we're superuser, we can set the replication model to 'streaming' to
+-- create a one-off MX table... but if we forget to set the replication factor to one,
+-- we should see an error reminding us to fix that
+SET citus.replication_model TO 'streaming';
+SELECT create_distributed_table('mx_table_test', 'col1');
+ERROR:  replication factors above one are incompatible with the streaming replication model
+HINT:  Try again after reducing "citus.shard_replication_factor" to one or setting "citus.replication_model" to "statement".
+-- ok, so now actually create the one-off MX table
+SET citus.shard_replication_factor TO 1;
 SELECT create_distributed_table('mx_table_test', 'col1');
  create_distributed_table 
 --------------------------
@@ -154,6 +160,7 @@ SELECT repmodel FROM pg_dist_partition WHERE logicalrelid='mx_table_test'::regcl
 (1 row)
 
 DROP TABLE mx_table_test;
+RESET citus.replication_model;
 -- Show that it is not possible to create an mx table with the old 
 -- master_create_distributed_table function
 CREATE TABLE mx_table_test (col1 int, col2 text);

src/test/regress/expected/multi_metadata_sync.out

@@ -267,7 +267,10 @@ SELECT count(*) FROM pg_trigger WHERE tgrelid='mx_testing_schema.mx_test_table':
 
 -- Make sure that start_metadata_sync_to_node considers foreign key constraints
 \c - - - :master_port
+-- Since we're superuser, we can set the replication model to 'streaming' to
+-- create some MX tables
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 CREATE SCHEMA mx_testing_schema_2;
 CREATE TABLE mx_testing_schema.fk_test_1 (col1 int, col2 text, col3 int, UNIQUE(col1, col3));
 CREATE TABLE mx_testing_schema_2.fk_test_2 (col1 int, col2 int, col3 text, 
@@ -307,6 +310,7 @@ Foreign-key constraints:
 DROP TABLE mx_testing_schema_2.fk_test_2;
 DROP TABLE mx_testing_schema.fk_test_1;
 RESET citus.shard_replication_factor;
+RESET citus.replication_model;
 -- Check that repeated calls to start_metadata_sync_to_node has no side effects
 \c - - - :master_port
 SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
@@ -399,6 +403,7 @@ SELECT hasmetadata FROM pg_dist_node WHERE nodeport=:worker_2_port;
 -- Check that the distributed table can be queried from the worker
 \c - - - :master_port
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
  start_metadata_sync_to_node 
 -----------------------------
@@ -489,6 +494,7 @@ CREATE SCHEMA mx_test_schema_1;
 CREATE SCHEMA mx_test_schema_2;
 -- Create MX tables
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 CREATE TABLE mx_test_schema_1.mx_table_1 (col1 int UNIQUE, col2 text);
 CREATE INDEX mx_index_1 ON mx_test_schema_1.mx_table_1 (col1);
 CREATE TABLE mx_test_schema_2.mx_table_2 (col1 int, col2 text);
@@ -754,6 +760,7 @@ SELECT nextval('pg_catalog.pg_dist_colocationid_seq') AS last_colocation_id \gse
 ALTER SEQUENCE pg_catalog.pg_dist_colocationid_seq RESTART 10000;
 SET citus.shard_count TO 7;
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 CREATE TABLE mx_colocation_test_1 (a int);
 SELECT create_distributed_table('mx_colocation_test_1', 'a');
  create_distributed_table 
@@ -848,6 +855,7 @@ DROP TABLE mx_colocation_test_2;
 \c - - - :master_port	
 SET citus.shard_count TO 7;
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 CREATE TABLE mx_temp_drop_test (a int);
 SELECT create_distributed_table('mx_temp_drop_test', 'a');
  create_distributed_table 
@@ -880,6 +888,7 @@ DROP TABLE mx_temp_drop_test;
 \c - - - :master_port	
 SET citus.shard_count TO 3;
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 SELECT stop_metadata_sync_to_node('localhost', :worker_1_port);
  stop_metadata_sync_to_node 
 ----------------------------
@@ -1097,7 +1106,8 @@ SELECT master_remove_node('localhost', :worker_2_port);
  
 (1 row)
 
-CREATE USER mx_user;
+ -- the master user needs superuser permissions to change the replication model
+CREATE USER mx_user WITH SUPERUSER;
 NOTICE:  not propagating CREATE ROLE/USER commands to worker nodes
 HINT:  Connect to worker nodes directly to manually create all necessary users and roles.
 \c - - - :worker_1_port
@@ -1112,6 +1122,7 @@ HINT:  Connect to worker nodes directly to manually create all necessary users a
 -- Create an mx table as a different user
 CREATE TABLE mx_table (a int, b BIGSERIAL);
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 SELECT create_distributed_table('mx_table', 'a');
  create_distributed_table 
 --------------------------
@@ -1352,6 +1363,7 @@ SELECT stop_metadata_sync_to_node('localhost', :worker_2_port);
 
 RESET citus.shard_count;
 RESET citus.shard_replication_factor;
+RESET citus.replication_model;
 RESET citus.multi_shard_commit_protocol;
 ALTER SEQUENCE pg_catalog.pg_dist_groupid_seq RESTART :last_group_id;
 ALTER SEQUENCE pg_catalog.pg_dist_node_nodeid_seq RESTART :last_node_id;

src/test/regress/expected/multi_replicate_reference_table.out

@@ -353,6 +353,7 @@ SELECT create_reference_table('replicate_reference_table_reference_one');
 
 SET citus.shard_count TO 1;
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 CREATE TABLE replicate_reference_table_hash(column1 int);
 SELECT create_distributed_table('replicate_reference_table_hash', 'column1');
  create_distributed_table 
@@ -605,3 +606,5 @@ DROP SCHEMA replicate_reference_table_schema CASCADE;
 -- reload pg_dist_shard_placement table
 INSERT INTO pg_dist_shard_placement (SELECT * FROM tmp_shard_placement);
 DROP TABLE tmp_shard_placement;
+RESET citus.shard_replication_factor;
+RESET citus.replication_model;

src/test/regress/expected/multi_table_ddl.out

@@ -33,6 +33,9 @@ ROLLBACK;
 DROP TABLE testtableddl;
 -- verify that the table can dropped even if shards exist
 CREATE TABLE testtableddl(somecol int, distributecol text NOT NULL);
+-- create table as MX table to do create empty shard test here, too
+SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 SELECT master_create_distributed_table('testtableddl', 'distributecol', 'append');
  master_create_distributed_table 
 ---------------------------------
@@ -45,7 +48,15 @@ SELECT 1 FROM master_create_empty_shard('testtableddl');
         1
 (1 row)
 
+-- this'll error out
+SET citus.shard_replication_factor TO 2;
+SELECT 1 FROM master_create_empty_shard('testtableddl');
+ERROR:  replication factors above one are incompatible with tables which use the streaming replication model
+HINT:  Try again after reducing "citus.shard_replication_factor" to one.
+-- now actually drop table and shards
 DROP TABLE testtableddl;
+RESET citus.shard_replication_factor;
+RESET citus.replication_model;
 -- ensure no metadata of distributed tables are remaining
 SELECT * FROM pg_dist_partition;
  logicalrelid | partmethod | partkey | colocationid | repmodel 

src/test/regress/expected/multi_unsupported_worker_operations.out

@@ -12,6 +12,7 @@ SELECT nextval('pg_catalog.pg_dist_colocationid_seq') AS last_colocation_id \gse
 ALTER SEQUENCE pg_catalog.pg_dist_colocationid_seq RESTART 150000;
 -- Prepare the environment
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 SET citus.shard_count TO 5;
 -- Create test tables
 CREATE TABLE mx_table (col_1 int, col_2 text, col_3 BIGSERIAL);
@@ -403,3 +404,5 @@ SELECT worker_drop_distributed_table(logicalrelid) FROM pg_dist_partition;
 
 \c - - - :master_port
 ALTER SEQUENCE pg_catalog.pg_dist_colocationid_seq RESTART :last_colocation_id;
+RESET citus.shard_replication_factor;
+RESET citus.replication_model;

src/test/regress/expected/multi_upgrade_reference_table.out

@@ -801,6 +801,7 @@ DROP TABLE upgrade_reference_table_transaction_commit;
 -- create an mx table
 SET citus.shard_count TO 1;
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 CREATE TABLE upgrade_reference_table_mx(column1 int);
 SELECT create_distributed_table('upgrade_reference_table_mx', 'column1');
  create_distributed_table 
@@ -911,6 +912,7 @@ DROP TABLE upgrade_reference_table_mx;
 -- test valid cases, do it with MX
 SET citus.shard_count TO 1;
 SET citus.shard_replication_factor TO 2;
+RESET citus.replication_model;
 CREATE TABLE upgrade_reference_table_mx(column1 int);
 SELECT create_distributed_table('upgrade_reference_table_mx', 'column1');
  create_distributed_table 

src/test/regress/sql/multi_create_table.sql

@@ -112,15 +112,22 @@ CREATE TABLE supplier_single_shard
 );
 SELECT master_create_distributed_table('supplier_single_shard', 's_suppkey', 'append');
 
--- Show that when a hash distributed table with replication factor=1 is created, it 
--- automatically marked as streaming replicated
-SET citus.shard_replication_factor TO 1;
-
 CREATE TABLE mx_table_test (col1 int, col2 text);
+
+-- Since we're superuser, we can set the replication model to 'streaming' to
+-- create a one-off MX table... but if we forget to set the replication factor to one,
+-- we should see an error reminding us to fix that
+SET citus.replication_model TO 'streaming';
+SELECT create_distributed_table('mx_table_test', 'col1');
+
+-- ok, so now actually create the one-off MX table
+SET citus.shard_replication_factor TO 1;
 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;
 
+RESET citus.replication_model;
+
 -- Show that it is not possible to create an mx table with the old 
 -- master_create_distributed_table function
 CREATE TABLE mx_table_test (col1 int, col2 text);

src/test/regress/sql/multi_metadata_sync.sql

@@ -89,7 +89,11 @@ SELECT count(*) FROM pg_trigger WHERE tgrelid='mx_testing_schema.mx_test_table':
 
 -- Make sure that start_metadata_sync_to_node considers foreign key constraints
 \c - - - :master_port
+
+-- Since we're superuser, we can set the replication model to 'streaming' to
+-- create some MX tables
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 
 CREATE SCHEMA mx_testing_schema_2;
 
@@ -111,6 +115,7 @@ DROP TABLE mx_testing_schema_2.fk_test_2;
 DROP TABLE mx_testing_schema.fk_test_1;
 
 RESET citus.shard_replication_factor;
+RESET citus.replication_model;
 
 -- Check that repeated calls to start_metadata_sync_to_node has no side effects
 \c - - - :master_port
@@ -136,6 +141,7 @@ SELECT hasmetadata FROM pg_dist_node WHERE nodeport=:worker_2_port;
 -- Check that the distributed table can be queried from the worker
 \c - - - :master_port
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
 
 CREATE TABLE mx_query_test (a int, b text, c int);
@@ -177,6 +183,7 @@ CREATE SCHEMA mx_test_schema_2;
 
 -- Create MX tables
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 CREATE TABLE mx_test_schema_1.mx_table_1 (col1 int UNIQUE, col2 text);
 CREATE INDEX mx_index_1 ON mx_test_schema_1.mx_table_1 (col1);
 
@@ -302,6 +309,7 @@ SELECT nextval('pg_catalog.pg_dist_colocationid_seq') AS last_colocation_id \gse
 ALTER SEQUENCE pg_catalog.pg_dist_colocationid_seq RESTART 10000;
 SET citus.shard_count TO 7;
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 
 CREATE TABLE mx_colocation_test_1 (a int);
 SELECT create_distributed_table('mx_colocation_test_1', 'a');
@@ -370,6 +378,7 @@ DROP TABLE mx_colocation_test_2;
 \c - - - :master_port	
 SET citus.shard_count TO 7;
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 
 CREATE TABLE mx_temp_drop_test (a int);
 SELECT create_distributed_table('mx_temp_drop_test', 'a');
@@ -387,6 +396,7 @@ DROP TABLE mx_temp_drop_test;
 \c - - - :master_port	
 SET citus.shard_count TO 3;
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 
 SELECT stop_metadata_sync_to_node('localhost', :worker_1_port);
 SELECT stop_metadata_sync_to_node('localhost', :worker_2_port);
@@ -465,7 +475,8 @@ DELETE FROM pg_dist_shard_placement;
 DELETE FROM pg_dist_partition;
 SELECT master_remove_node('localhost', :worker_2_port);
 
-CREATE USER mx_user;
+ -- the master user needs superuser permissions to change the replication model
+CREATE USER mx_user WITH SUPERUSER;
 \c - - - :worker_1_port
 CREATE USER mx_user;
 \c - - - :worker_2_port
@@ -475,6 +486,7 @@ CREATE USER mx_user;
 -- Create an mx table as a different user
 CREATE TABLE mx_table (a int, b BIGSERIAL);
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 SELECT create_distributed_table('mx_table', 'a');
 
 \c - postgres - :master_port
@@ -591,6 +603,7 @@ SELECT stop_metadata_sync_to_node('localhost', :worker_2_port);
 
 RESET citus.shard_count;
 RESET citus.shard_replication_factor;
+RESET citus.replication_model;
 RESET citus.multi_shard_commit_protocol;
 
 ALTER SEQUENCE pg_catalog.pg_dist_groupid_seq RESTART :last_group_id;

src/test/regress/sql/multi_replicate_reference_table.sql

@@ -228,6 +228,7 @@ SELECT create_reference_table('replicate_reference_table_reference_one');
 
 SET citus.shard_count TO 1;
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 CREATE TABLE replicate_reference_table_hash(column1 int);
 SELECT create_distributed_table('replicate_reference_table_hash', 'column1');
 
@@ -395,3 +396,6 @@ DROP SCHEMA replicate_reference_table_schema CASCADE;
 -- reload pg_dist_shard_placement table
 INSERT INTO pg_dist_shard_placement (SELECT * FROM tmp_shard_placement);
 DROP TABLE tmp_shard_placement;
+
+RESET citus.shard_replication_factor;
+RESET citus.replication_model;

src/test/regress/sql/multi_table_ddl.sql

@@ -32,10 +32,23 @@ DROP TABLE testtableddl;
 
 -- verify that the table can dropped even if shards exist
 CREATE TABLE testtableddl(somecol int, distributecol text NOT NULL);
+
+-- create table as MX table to do create empty shard test here, too
+SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 SELECT master_create_distributed_table('testtableddl', 'distributecol', 'append');
 SELECT 1 FROM master_create_empty_shard('testtableddl');
+
+-- this'll error out
+SET citus.shard_replication_factor TO 2;
+SELECT 1 FROM master_create_empty_shard('testtableddl');
+
+-- now actually drop table and shards
 DROP TABLE testtableddl;
 
+RESET citus.shard_replication_factor;
+RESET citus.replication_model;
+
 -- ensure no metadata of distributed tables are remaining
 SELECT * FROM pg_dist_partition;
 SELECT * FROM pg_dist_shard;

src/test/regress/sql/multi_unsupported_worker_operations.sql

@@ -16,6 +16,7 @@ ALTER SEQUENCE pg_catalog.pg_dist_colocationid_seq RESTART 150000;
 
 -- Prepare the environment
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 SET citus.shard_count TO 5;
 
 -- Create test tables
@@ -213,3 +214,6 @@ DELETE FROM pg_dist_node;
 SELECT worker_drop_distributed_table(logicalrelid) FROM pg_dist_partition;
 \c - - - :master_port
 ALTER SEQUENCE pg_catalog.pg_dist_colocationid_seq RESTART :last_colocation_id;
+
+RESET citus.shard_replication_factor;
+RESET citus.replication_model;

src/test/regress/sql/multi_upgrade_reference_table.sql

@@ -522,6 +522,7 @@ DROP TABLE upgrade_reference_table_transaction_commit;
 -- create an mx table
 SET citus.shard_count TO 1;
 SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
 CREATE TABLE upgrade_reference_table_mx(column1 int);
 SELECT create_distributed_table('upgrade_reference_table_mx', 'column1');
 
@@ -596,6 +597,7 @@ DROP TABLE upgrade_reference_table_mx;
 -- test valid cases, do it with MX
 SET citus.shard_count TO 1;
 SET citus.shard_replication_factor TO 2;
+RESET citus.replication_model;
 CREATE TABLE upgrade_reference_table_mx(column1 int);
 SELECT create_distributed_table('upgrade_reference_table_mx', 'column1');
 UPDATE pg_dist_shard_placement SET shardstate = 3