From a69abe3be0dee728111d942a966838ad2c2b1bd2 Mon Sep 17 00:00:00 2001
From: Naisila Puka <37271756+naisila@users.noreply.github.com>
Date: Thu, 9 Sep 2021 23:41:07 +0300
Subject: [PATCH] Fixes bug about int and smallint sequences on MX (#5254)

* Introduce worker_nextval udf for int&smallint column defaults

* Fix current tests and add new ones for worker_nextval
---
 .../distributed/commands/alter_table.c        |   4 +-
 .../citus_add_local_table_to_metadata.c       |   2 +-
 src/backend/distributed/commands/table.c      | 135 +++++++++-
 .../distributed/commands/utility_hook.c       |   5 +-
 .../distributed/deparser/citus_ruleutils.c    |  29 +-
 .../distributed/metadata/metadata_sync.c      |  16 +-
 .../distributed/operations/node_protocol.c    |  14 +-
 .../distributed/operations/repair_shards.c    |   2 +-
 .../distributed/operations/stage_protocol.c   |   4 +-
 .../distributed/sql/citus--10.1-1--10.2-1.sql |   1 +
 .../sql/downgrades/citus--10.2-1--10.1-1.sql  |   1 +
 .../sql/udfs/worker_nextval/10.2-1.sql        |   6 +
 .../sql/udfs/worker_nextval/latest.sql        |   6 +
 .../worker/worker_data_fetch_protocol.c       |  36 ++-
 src/include/distributed/citus_ruleutils.h     |   4 +-
 src/include/distributed/commands.h            |   1 +
 .../distributed/coordinator_protocol.h        |  26 +-
 src/include/distributed/worker_protocol.h     |   2 +
 src/test/regress/expected/multi_extension.out |   3 +-
 .../regress/expected/multi_metadata_sync.out  |  30 ++-
 .../expected/multi_sequence_default.out       | 255 +++++++++++++++---
 .../expected/upgrade_list_citus_objects.out   |   3 +-
 src/test/regress/sql/multi_metadata_sync.sql  |  11 +
 .../regress/sql/multi_sequence_default.sql    | 101 ++++++-
 24 files changed, 596 insertions(+), 101 deletions(-)
 create mode 100644 src/backend/distributed/sql/udfs/worker_nextval/10.2-1.sql
 create mode 100644 src/backend/distributed/sql/udfs/worker_nextval/latest.sql

diff --git a/src/backend/distributed/commands/alter_table.c b/src/backend/distributed/commands/alter_table.c
index 0f3a2be3b..df105c1e8 100644
--- a/src/backend/distributed/commands/alter_table.c
+++ b/src/backend/distributed/commands/alter_table.c
@@ -539,7 +539,9 @@ ConvertTable(TableConversionState *con)
 	}
 	char *newAccessMethod = con->accessMethod ? con->accessMethod :
 							con->originalAccessMethod;
-	List *preLoadCommands = GetPreLoadTableCreationCommands(con->relationId, true,
+	IncludeSequenceDefaults includeSequenceDefaults = NEXTVAL_SEQUENCE_DEFAULTS;
+	List *preLoadCommands = GetPreLoadTableCreationCommands(con->relationId,
+															includeSequenceDefaults,
 															newAccessMethod);
 
 	if (con->accessMethod && strcmp(con->accessMethod, "columnar") == 0)
diff --git a/src/backend/distributed/commands/citus_add_local_table_to_metadata.c b/src/backend/distributed/commands/citus_add_local_table_to_metadata.c
index 6dfe6cbc9..303f2ea3a 100644
--- a/src/backend/distributed/commands/citus_add_local_table_to_metadata.c
+++ b/src/backend/distributed/commands/citus_add_local_table_to_metadata.c
@@ -463,7 +463,7 @@ GetShellTableDDLEventsForCitusLocalTable(Oid relationId)
 	 * Include DEFAULT clauses for columns getting their default values from
 	 * a sequence.
 	 */
-	bool includeSequenceDefaults = true;
+	IncludeSequenceDefaults includeSequenceDefaults = NEXTVAL_SEQUENCE_DEFAULTS;
 
 	List *tableDDLCommands = GetFullTableCreationCommands(relationId,
 														  includeSequenceDefaults);
diff --git a/src/backend/distributed/commands/table.c b/src/backend/distributed/commands/table.c
index 81fe8935e..e5a8101ea 100644
--- a/src/backend/distributed/commands/table.c
+++ b/src/backend/distributed/commands/table.c
@@ -42,6 +42,7 @@
 #include "lib/stringinfo.h"
 #include "nodes/parsenodes.h"
 #include "parser/parse_expr.h"
+#include "parser/parse_type.h"
 #include "storage/lmgr.h"
 #include "utils/builtins.h"
 #include "utils/fmgroids.h"
@@ -95,8 +96,11 @@ static void SetInterShardDDLTaskPlacementList(Task *task,
 static void SetInterShardDDLTaskRelationShardList(Task *task,
 												  ShardInterval *leftShardInterval,
 												  ShardInterval *rightShardInterval);
-static Oid GetSequenceOid(Oid relationId, AttrNumber attnum);
 static Oid get_attrdef_oid(Oid relationId, AttrNumber attnum);
+static char * GetAlterColumnWithNextvalDefaultCmd(Oid sequenceOid, Oid relationId,
+												  char *colname);
+static char * GetAddColumnWithNextvalDefaultCmd(Oid sequenceOid, Oid relationId,
+												char *colname, TypeName *typeName);
 
 
 /*
@@ -654,6 +658,14 @@ PreprocessAlterTableStmt(Node *node, const char *alterTableCommand,
 	 */
 	bool deparseAT = false;
 	bool propagateCommandToWorkers = true;
+
+	/*
+	 * Sometimes we want to run a different DDL Command string in MX workers
+	 * For example, in cases where worker_nextval should be used instead
+	 * of nextval() in column defaults with type int and smallint
+	 */
+	bool useInitialDDLCommandString = true;
+
 	AlterTableStmt *newStmt = copyObject(alterTableStatement);
 
 	AlterTableCmd *newCmd = makeNode(AlterTableCmd);
@@ -763,6 +775,7 @@ PreprocessAlterTableStmt(Node *node, const char *alterTableCommand,
 						if (contain_nextval_expression_walker(expr, NULL))
 						{
 							deparseAT = true;
+							useInitialDDLCommandString = false;
 
 							/* the new column definition will have no constraint */
 							ColumnDef *newColDef = copyObject(columnDefinition);
@@ -832,6 +845,7 @@ PreprocessAlterTableStmt(Node *node, const char *alterTableCommand,
 			if (contain_nextval_expression_walker(expr, NULL))
 			{
 				propagateCommandToWorkers = false;
+				useInitialDDLCommandString = false;
 			}
 		}
 		else if (alterTableType == AT_AttachPartition)
@@ -928,7 +942,7 @@ PreprocessAlterTableStmt(Node *node, const char *alterTableCommand,
 		sqlForTaskList = DeparseTreeNode((Node *) newStmt);
 	}
 
-	ddlJob->commandString = alterTableCommand;
+	ddlJob->commandString = useInitialDDLCommandString ? alterTableCommand : NULL;
 
 	if (OidIsValid(rightRelationId))
 	{
@@ -1640,6 +1654,11 @@ PostprocessAlterTableStmt(AlterTableStmt *alterTableStatement)
 		EnsureDependenciesExistOnAllNodes(&tableAddress);
 	}
 
+	/* for the new sequences coming with this ALTER TABLE statement */
+	bool needMetadataSyncForNewSequences = false;
+
+	char *alterTableDefaultNextvalCmd = NULL;
+
 	List *commandList = alterTableStatement->cmds;
 	AlterTableCmd *command = NULL;
 	foreach_ptr(command, commandList)
@@ -1728,8 +1747,16 @@ PostprocessAlterTableStmt(AlterTableStmt *alterTableStatement)
 								if (ShouldSyncTableMetadata(relationId) &&
 									ClusterHasKnownMetadataWorkers())
 								{
+									needMetadataSyncForNewSequences = true;
 									MarkSequenceDistributedAndPropagateDependencies(
 										seqOid);
+									alterTableDefaultNextvalCmd =
+										GetAddColumnWithNextvalDefaultCmd(seqOid,
+																		  relationId,
+																		  columnDefinition
+																		  ->colname,
+																		  columnDefinition
+																		  ->typeName);
 								}
 							}
 						}
@@ -1761,15 +1788,17 @@ PostprocessAlterTableStmt(AlterTableStmt *alterTableStatement)
 					if (ShouldSyncTableMetadata(relationId) &&
 						ClusterHasKnownMetadataWorkers())
 					{
+						needMetadataSyncForNewSequences = true;
 						MarkSequenceDistributedAndPropagateDependencies(seqOid);
+						alterTableDefaultNextvalCmd = GetAlterColumnWithNextvalDefaultCmd(
+							seqOid, relationId, command->name);
 					}
 				}
 			}
 		}
 	}
 
-	/* for the new sequences coming with this ALTER TABLE statement */
-	if (ShouldSyncTableMetadata(relationId) && ClusterHasKnownMetadataWorkers())
+	if (needMetadataSyncForNewSequences)
 	{
 		List *sequenceCommandList = NIL;
 
@@ -1787,6 +1816,16 @@ PostprocessAlterTableStmt(AlterTableStmt *alterTableStatement)
 			SendCommandToWorkersWithMetadata(sequenceCommand);
 		}
 
+		/*
+		 * It's easy to retrieve the sequence id to create the proper commands
+		 * in postprocess, after the dependency between the sequence and the table
+		 * has been created. We already return ddlJobs in PreprocessAlterTableStmt,
+		 * hence we can't return ddlJobs in PostprocessAlterTableStmt.
+		 * That's why we execute the following here instead of
+		 * in ExecuteDistributedDDLJob
+		 */
+		SendCommandToWorkersWithMetadata(alterTableDefaultNextvalCmd);
+
 		SendCommandToWorkersWithMetadata(ENABLE_DDL_PROPAGATION);
 	}
 }
@@ -1797,7 +1836,7 @@ PostprocessAlterTableStmt(AlterTableStmt *alterTableStatement)
  * of the attribute with given attnum of the given table relationId
  * If there is no sequence used it returns InvalidOid.
  */
-static Oid
+Oid
 GetSequenceOid(Oid relationId, AttrNumber attnum)
 {
 	/* get attrdefoid from the given relationId and attnum */
@@ -1821,15 +1860,10 @@ GetSequenceOid(Oid relationId, AttrNumber attnum)
 	if (list_length(sequencesFromAttrDef) > 1)
 	{
 		/* to simplify and eliminate cases like "DEFAULT nextval('..') - nextval('..')" */
-		if (IsCitusTableType(relationId, CITUS_LOCAL_TABLE))
-		{
-			ereport(ERROR, (errmsg(
-								"More than one sequence in a column default"
-								" is not supported for adding local tables to metadata")));
-		}
 		ereport(ERROR, (errmsg(
 							"More than one sequence in a column default"
-							" is not supported for distribution")));
+							" is not supported for distribution "
+							"or for adding local tables to metadata")));
 	}
 
 	return lfirst_oid(list_head(sequencesFromAttrDef));
@@ -1886,6 +1920,83 @@ get_attrdef_oid(Oid relationId, AttrNumber attnum)
 }
 
 
+/*
+ * GetAlterColumnWithNextvalDefaultCmd returns a string representing:
+ * ALTER TABLE ALTER COLUMN .. SET DEFAULT nextval()
+ * If sequence type is not bigint, we use worker_nextval() instead of nextval().
+ */
+static char *
+GetAlterColumnWithNextvalDefaultCmd(Oid sequenceOid, Oid relationId, char *colname)
+{
+	char *qualifiedSequenceName = generate_qualified_relation_name(sequenceOid);
+	char *qualifiedRelationName = generate_qualified_relation_name(relationId);
+
+	char *nextvalFunctionName = "nextval";
+	bool useWorkerNextval = (pg_get_sequencedef(sequenceOid)->seqtypid != INT8OID);
+	if (useWorkerNextval)
+	{
+		/*
+		 * We use worker_nextval for int and smallint types.
+		 * Check issue #5126 and PR #5254 for details.
+		 * https://github.com/citusdata/citus/issues/5126
+		 */
+		nextvalFunctionName = "worker_nextval";
+	}
+
+	StringInfoData str = { 0 };
+	initStringInfo(&str);
+	appendStringInfo(&str, "ALTER TABLE %s ALTER COLUMN %s "
+						   "SET DEFAULT %s(%s::regclass)",
+					 qualifiedRelationName, colname,
+					 quote_qualified_identifier("pg_catalog", nextvalFunctionName),
+					 quote_literal_cstr(qualifiedSequenceName));
+
+	return str.data;
+}
+
+
+/*
+ * GetAddColumnWithNextvalDefaultCmd returns a string representing:
+ * ALTER TABLE ADD COLUMN .. DEFAULT nextval()
+ * If sequence type is not bigint, we use worker_nextval() instead of nextval().
+ */
+static char *
+GetAddColumnWithNextvalDefaultCmd(Oid sequenceOid, Oid relationId, char *colname,
+								  TypeName *typeName)
+{
+	char *qualifiedSequenceName = generate_qualified_relation_name(sequenceOid);
+	char *qualifiedRelationName = generate_qualified_relation_name(relationId);
+
+	char *nextvalFunctionName = "nextval";
+	bool useWorkerNextval = (pg_get_sequencedef(sequenceOid)->seqtypid != INT8OID);
+	if (useWorkerNextval)
+	{
+		/*
+		 * We use worker_nextval for int and smallint types.
+		 * Check issue #5126 and PR #5254 for details.
+		 * https://github.com/citusdata/citus/issues/5126
+		 */
+		nextvalFunctionName = "worker_nextval";
+	}
+
+	int32 typmod = 0;
+	Oid typeOid = InvalidOid;
+	bits16 formatFlags = FORMAT_TYPE_TYPEMOD_GIVEN | FORMAT_TYPE_FORCE_QUALIFY;
+	typenameTypeIdAndMod(NULL, typeName, &typeOid, &typmod);
+
+	StringInfoData str = { 0 };
+	initStringInfo(&str);
+	appendStringInfo(&str,
+					 "ALTER TABLE %s ADD COLUMN %s %s "
+					 "DEFAULT %s(%s::regclass)", qualifiedRelationName, colname,
+					 format_type_extended(typeOid, typmod, formatFlags),
+					 quote_qualified_identifier("pg_catalog", nextvalFunctionName),
+					 quote_literal_cstr(qualifiedSequenceName));
+
+	return str.data;
+}
+
+
 void
 ErrorUnsupportedAlterTableAddColumn(Oid relationId, AlterTableCmd *command,
 									Constraint *constraint)
diff --git a/src/backend/distributed/commands/utility_hook.c b/src/backend/distributed/commands/utility_hook.c
index 82837ba59..12fdc5f45 100644
--- a/src/backend/distributed/commands/utility_hook.c
+++ b/src/backend/distributed/commands/utility_hook.c
@@ -891,7 +891,10 @@ ExecuteDistributedDDLJob(DDLJob *ddlJob)
 				SendCommandToWorkersWithMetadata(setSearchPathCommand);
 			}
 
-			SendCommandToWorkersWithMetadata((char *) ddlJob->commandString);
+			if (ddlJob->commandString != NULL)
+			{
+				SendCommandToWorkersWithMetadata((char *) ddlJob->commandString);
+			}
 		}
 
 		ExecuteUtilityTaskList(ddlJob->taskList, localExecutionSupported);
diff --git a/src/backend/distributed/deparser/citus_ruleutils.c b/src/backend/distributed/deparser/citus_ruleutils.c
index 6e185eda1..88b12deb1 100644
--- a/src/backend/distributed/deparser/citus_ruleutils.c
+++ b/src/backend/distributed/deparser/citus_ruleutils.c
@@ -251,12 +251,14 @@ pg_get_sequencedef(Oid sequenceRelationId)
  * definition includes table's schema, default column values, not null and check
  * constraints. The definition does not include constraints that trigger index
  * creations; specifically, unique and primary key constraints are excluded.
- * When the flag includeSequenceDefaults is set, the function also creates
+ * When includeSequenceDefaults is NEXTVAL_SEQUENCE_DEFAULTS, the function also creates
  * DEFAULT clauses for columns getting their default values from a sequence.
+ * When it's WORKER_NEXTVAL_SEQUENCE_DEFAULTS, the function creates the DEFAULT
+ * clause using worker_nextval('sequence') and not nextval('sequence')
  */
 char *
-pg_get_tableschemadef_string(Oid tableRelationId, bool includeSequenceDefaults,
-							 char *accessMethod)
+pg_get_tableschemadef_string(Oid tableRelationId, IncludeSequenceDefaults
+							 includeSequenceDefaults, char *accessMethod)
 {
 	bool firstAttributePrinted = false;
 	AttrNumber defaultValueIndex = 0;
@@ -374,7 +376,26 @@ pg_get_tableschemadef_string(Oid tableRelationId, bool includeSequenceDefaults,
 					}
 					else
 					{
-						appendStringInfo(&buffer, " DEFAULT %s", defaultString);
+						Oid seqOid = GetSequenceOid(tableRelationId, defaultValue->adnum);
+						if (includeSequenceDefaults == WORKER_NEXTVAL_SEQUENCE_DEFAULTS &&
+							seqOid != InvalidOid &&
+							pg_get_sequencedef(seqOid)->seqtypid != INT8OID)
+						{
+							/*
+							 * We use worker_nextval for int and smallint types.
+							 * Check issue #5126 and PR #5254 for details.
+							 * https://github.com/citusdata/citus/issues/5126
+							 */
+							char *sequenceName = generate_qualified_relation_name(
+								seqOid);
+							appendStringInfo(&buffer,
+											 " DEFAULT worker_nextval(%s::regclass)",
+											 quote_literal_cstr(sequenceName));
+						}
+						else
+						{
+							appendStringInfo(&buffer, " DEFAULT %s", defaultString);
+						}
 					}
 				}
 			}
diff --git a/src/backend/distributed/metadata/metadata_sync.c b/src/backend/distributed/metadata/metadata_sync.c
index 6fe5ac58d..87d0528f5 100644
--- a/src/backend/distributed/metadata/metadata_sync.c
+++ b/src/backend/distributed/metadata/metadata_sync.c
@@ -497,7 +497,7 @@ MetadataCreateCommands(void)
 	List *propagatedTableList = NIL;
 	bool includeNodesFromOtherClusters = true;
 	List *workerNodeList = ReadDistNode(includeNodesFromOtherClusters);
-	bool includeSequenceDefaults = true;
+	IncludeSequenceDefaults includeSequenceDefaults = WORKER_NEXTVAL_SEQUENCE_DEFAULTS;
 
 	/* make sure we have deterministic output for our tests */
 	workerNodeList = SortList(workerNodeList, CompareWorkerNodes);
@@ -651,7 +651,7 @@ GetDistributedTableDDLEvents(Oid relationId)
 	CitusTableCacheEntry *cacheEntry = GetCitusTableCacheEntry(relationId);
 
 	List *commandList = NIL;
-	bool includeSequenceDefaults = true;
+	IncludeSequenceDefaults includeSequenceDefaults = WORKER_NEXTVAL_SEQUENCE_DEFAULTS;
 
 	/* if the table is owned by an extension we only propagate pg_dist_* records */
 	bool tableOwnedByExtension = IsTableOwnedByExtension(relationId);
@@ -1287,14 +1287,10 @@ GetDependentSequencesWithRelation(Oid relationId, List **attnumList,
 		/* to simplify and eliminate cases like "DEFAULT nextval('..') - nextval('..')" */
 		if (list_length(sequencesFromAttrDef) > 1)
 		{
-			if (IsCitusTableType(relationId, CITUS_LOCAL_TABLE))
-			{
-				ereport(ERROR, (errmsg(
-									"More than one sequence in a column default"
-									" is not supported for adding local tables to metadata")));
-			}
-			ereport(ERROR, (errmsg("More than one sequence in a column default"
-								   " is not supported for distribution")));
+			ereport(ERROR, (errmsg(
+								"More than one sequence in a column default"
+								" is not supported for distribution "
+								"or for adding local tables to metadata")));
 		}
 
 		if (list_length(sequencesFromAttrDef) == 1)
diff --git a/src/backend/distributed/operations/node_protocol.c b/src/backend/distributed/operations/node_protocol.c
index 1638489e7..5c09ee59f 100644
--- a/src/backend/distributed/operations/node_protocol.c
+++ b/src/backend/distributed/operations/node_protocol.c
@@ -216,7 +216,7 @@ master_get_table_ddl_events(PG_FUNCTION_ARGS)
 	{
 		text *relationName = PG_GETARG_TEXT_P(0);
 		Oid relationId = ResolveRelationId(relationName, false);
-		bool includeSequenceDefaults = true;
+		IncludeSequenceDefaults includeSequenceDefaults = NEXTVAL_SEQUENCE_DEFAULTS;
 
 
 		/* create a function context for cross-call persistence */
@@ -533,16 +533,19 @@ ResolveRelationId(text *relationName, bool missingOk)
 
 
 /*
- * GetFullTableCreationCommands takes in a relationId, includeSequenceDefaults flag,
+ * GetFullTableCreationCommands takes in a relationId, includeSequenceDefaults,
  * and returns the list of DDL commands needed to reconstruct the relation.
- * When the flag includeSequenceDefaults is set, the function also creates
+ * When includeSequenceDefaults is NEXTVAL_SEQUENCE_DEFAULTS, the function also creates
  * DEFAULT clauses for columns getting their default values from a sequence.
+ * When it's WORKER_NEXTVAL_SEQUENCE_DEFAULTS, the function creates the DEFAULT
+ * clause using worker_nextval('sequence') and not nextval('sequence')
  * These DDL commands are all palloced; and include the table's schema
  * definition, optional column storage and statistics definitions, and index
  * constraint and trigger definitions.
  */
 List *
-GetFullTableCreationCommands(Oid relationId, bool includeSequenceDefaults)
+GetFullTableCreationCommands(Oid relationId, IncludeSequenceDefaults
+							 includeSequenceDefaults)
 {
 	List *tableDDLEventList = NIL;
 
@@ -651,7 +654,8 @@ GetTableReplicaIdentityCommand(Oid relationId)
  * to facilitate faster data load.
  */
 List *
-GetPreLoadTableCreationCommands(Oid relationId, bool includeSequenceDefaults,
+GetPreLoadTableCreationCommands(Oid relationId,
+								IncludeSequenceDefaults includeSequenceDefaults,
 								char *accessMethod)
 {
 	List *tableDDLEventList = NIL;
diff --git a/src/backend/distributed/operations/repair_shards.c b/src/backend/distributed/operations/repair_shards.c
index 2784e6958..8a7a276f0 100644
--- a/src/backend/distributed/operations/repair_shards.c
+++ b/src/backend/distributed/operations/repair_shards.c
@@ -1453,7 +1453,7 @@ RecreateTableDDLCommandList(Oid relationId)
 
 	StringInfo dropCommand = makeStringInfo();
 	char relationKind = get_rel_relkind(relationId);
-	bool includeSequenceDefaults = false;
+	IncludeSequenceDefaults includeSequenceDefaults = NO_SEQUENCE_DEFAULTS;
 
 	/* build appropriate DROP command based on relation kind */
 	if (RegularTable(relationId))
diff --git a/src/backend/distributed/operations/stage_protocol.c b/src/backend/distributed/operations/stage_protocol.c
index a6b9c04da..66ee281ba 100644
--- a/src/backend/distributed/operations/stage_protocol.c
+++ b/src/backend/distributed/operations/stage_protocol.c
@@ -455,7 +455,7 @@ CreateAppendDistributedShardPlacements(Oid relationId, int64 shardId,
 	int placementsCreated = 0;
 	List *foreignConstraintCommandList =
 		GetReferencingForeignConstaintCommands(relationId);
-	bool includeSequenceDefaults = false;
+	IncludeSequenceDefaults includeSequenceDefaults = NO_SEQUENCE_DEFAULTS;
 	List *ddlCommandList = GetFullTableCreationCommands(relationId,
 														includeSequenceDefaults);
 	uint32 connectionFlag = FOR_DDL;
@@ -568,7 +568,7 @@ void
 CreateShardsOnWorkers(Oid distributedRelationId, List *shardPlacements,
 					  bool useExclusiveConnection, bool colocatedShard)
 {
-	bool includeSequenceDefaults = false;
+	IncludeSequenceDefaults includeSequenceDefaults = NO_SEQUENCE_DEFAULTS;
 	List *ddlCommandList = GetFullTableCreationCommands(distributedRelationId,
 														includeSequenceDefaults);
 	List *foreignConstraintCommandList =
diff --git a/src/backend/distributed/sql/citus--10.1-1--10.2-1.sql b/src/backend/distributed/sql/citus--10.1-1--10.2-1.sql
index 8c219ee68..507a141c5 100644
--- a/src/backend/distributed/sql/citus--10.1-1--10.2-1.sql
+++ b/src/backend/distributed/sql/citus--10.1-1--10.2-1.sql
@@ -19,6 +19,7 @@ ALTER TABLE pg_catalog.pg_dist_placement ADD CONSTRAINT placement_shardid_groupi
 #include "udfs/create_time_partitions/10.2-1.sql"
 #include "udfs/drop_old_time_partitions/10.2-1.sql"
 #include "udfs/get_missing_time_partition_ranges/10.2-1.sql"
+#include "udfs/worker_nextval/10.2-1.sql"
 
 DROP FUNCTION pg_catalog.citus_drop_all_shards(regclass, text, text);
 CREATE FUNCTION pg_catalog.citus_drop_all_shards(logicalrelid regclass,
diff --git a/src/backend/distributed/sql/downgrades/citus--10.2-1--10.1-1.sql b/src/backend/distributed/sql/downgrades/citus--10.2-1--10.1-1.sql
index 6fba9d8fd..1e47b42c4 100644
--- a/src/backend/distributed/sql/downgrades/citus--10.2-1--10.1-1.sql
+++ b/src/backend/distributed/sql/downgrades/citus--10.2-1--10.1-1.sql
@@ -19,6 +19,7 @@ DROP FUNCTION pg_catalog.citus_internal_delete_shard_metadata(bigint);
 DROP FUNCTION pg_catalog.citus_internal_update_relation_colocation(oid, integer);
 DROP FUNCTION pg_catalog.create_time_partitions(regclass, interval, timestamp with time zone, timestamp with time zone);
 DROP FUNCTION pg_catalog.get_missing_time_partition_ranges(regclass, interval, timestamp with time zone, timestamp with time zone);
+DROP FUNCTION pg_catalog.worker_nextval(regclass);
 
 DROP PROCEDURE pg_catalog.drop_old_time_partitions(regclass, timestamptz);
 
diff --git a/src/backend/distributed/sql/udfs/worker_nextval/10.2-1.sql b/src/backend/distributed/sql/udfs/worker_nextval/10.2-1.sql
new file mode 100644
index 000000000..47aa8101b
--- /dev/null
+++ b/src/backend/distributed/sql/udfs/worker_nextval/10.2-1.sql
@@ -0,0 +1,6 @@
+CREATE FUNCTION pg_catalog.worker_nextval(sequence regclass)
+    RETURNS int
+    LANGUAGE C STRICT
+    AS 'MODULE_PATHNAME', $$worker_nextval$$;
+COMMENT ON FUNCTION pg_catalog.worker_nextval(regclass)
+    IS 'calculates nextval() for column defaults of type int or smallint';
diff --git a/src/backend/distributed/sql/udfs/worker_nextval/latest.sql b/src/backend/distributed/sql/udfs/worker_nextval/latest.sql
new file mode 100644
index 000000000..47aa8101b
--- /dev/null
+++ b/src/backend/distributed/sql/udfs/worker_nextval/latest.sql
@@ -0,0 +1,6 @@
+CREATE FUNCTION pg_catalog.worker_nextval(sequence regclass)
+    RETURNS int
+    LANGUAGE C STRICT
+    AS 'MODULE_PATHNAME', $$worker_nextval$$;
+COMMENT ON FUNCTION pg_catalog.worker_nextval(regclass)
+    IS 'calculates nextval() for column defaults of type int or smallint';
diff --git a/src/backend/distributed/worker/worker_data_fetch_protocol.c b/src/backend/distributed/worker/worker_data_fetch_protocol.c
index 187eeee05..efdc2da85 100644
--- a/src/backend/distributed/worker/worker_data_fetch_protocol.c
+++ b/src/backend/distributed/worker/worker_data_fetch_protocol.c
@@ -77,6 +77,7 @@ PG_FUNCTION_INFO_V1(worker_apply_shard_ddl_command);
 PG_FUNCTION_INFO_V1(worker_apply_inter_shard_ddl_command);
 PG_FUNCTION_INFO_V1(worker_apply_sequence_command);
 PG_FUNCTION_INFO_V1(worker_append_table_to_shard);
+PG_FUNCTION_INFO_V1(worker_nextval);
 
 /*
  * Following UDFs are stub functions, you can check their comments for more
@@ -700,6 +701,21 @@ worker_append_table_to_shard(PG_FUNCTION_ARGS)
 }
 
 
+/*
+ * worker_nextval calculates nextval() in worker nodes
+ * for int and smallint column default types
+ * TODO: not error out but get the proper nextval()
+ */
+Datum
+worker_nextval(PG_FUNCTION_ARGS)
+{
+	ereport(ERROR, (errmsg(
+						"nextval(sequence) calls in worker nodes are not supported"
+						" for column defaults of type int or smallint")));
+	PG_RETURN_INT32(0);
+}
+
+
 /*
  * check_log_statement is a copy of postgres' check_log_statement function and
  * returns whether a statement ought to be logged or not.
@@ -755,14 +771,20 @@ AlterSequenceMinMax(Oid sequenceId, char *schemaName, char *sequenceName,
 	int64 sequenceMinValue = sequenceData->seqmin;
 	int valueBitLength = 48;
 
-	/* for smaller types, put the group ID into the first 4 bits */
-	if (sequenceTypeId == INT4OID)
+	/*
+	 * For int and smallint, we don't currently support insertion from workers
+	 * Check issue #5126 and PR #5254 for details.
+	 * https://github.com/citusdata/citus/issues/5126
+	 * So, no need to alter sequence min/max for now
+	 * We call setval(sequence, maxvalue) such that manually using
+	 * nextval(sequence) in the workers will error out as well.
+	 */
+	if (sequenceTypeId != INT8OID)
 	{
-		valueBitLength = 28;
-	}
-	else if (sequenceTypeId == INT2OID)
-	{
-		valueBitLength = 12;
+		DirectFunctionCall2(setval_oid,
+							ObjectIdGetDatum(sequenceId),
+							Int64GetDatum(sequenceMaxValue));
+		return;
 	}
 
 	/* calculate min/max values that the sequence can generate in this worker */
diff --git a/src/include/distributed/citus_ruleutils.h b/src/include/distributed/citus_ruleutils.h
index fac19352d..946839181 100644
--- a/src/include/distributed/citus_ruleutils.h
+++ b/src/include/distributed/citus_ruleutils.h
@@ -15,6 +15,7 @@
 
 #include "catalog/pg_sequence.h"
 #include "commands/sequence.h"
+#include "distributed/coordinator_protocol.h"
 #include "lib/stringinfo.h"
 #include "nodes/parsenodes.h"
 #include "nodes/pg_list.h"
@@ -31,7 +32,8 @@ extern Oid get_extension_schema(Oid ext_oid);
 extern char * pg_get_serverdef_string(Oid tableRelationId);
 extern char * pg_get_sequencedef_string(Oid sequenceRelid);
 extern Form_pg_sequence pg_get_sequencedef(Oid sequenceRelationId);
-extern char * pg_get_tableschemadef_string(Oid tableRelationId, bool forShardCreation,
+extern char * pg_get_tableschemadef_string(Oid tableRelationId,
+										   IncludeSequenceDefaults includeSequenceDefaults,
 										   char *accessMethod);
 extern void EnsureRelationKindSupported(Oid relationId);
 extern char * pg_get_tablecolumnoptionsdef_string(Oid tableRelationId);
diff --git a/src/include/distributed/commands.h b/src/include/distributed/commands.h
index bb73e8764..7b0b2f5f2 100644
--- a/src/include/distributed/commands.h
+++ b/src/include/distributed/commands.h
@@ -422,6 +422,7 @@ extern void ErrorIfUnsupportedConstraint(Relation relation, char distributionMet
 extern ObjectAddress AlterTableSchemaStmtObjectAddress(Node *stmt,
 													   bool missing_ok);
 extern List * MakeNameListFromRangeVar(const RangeVar *rel);
+extern Oid GetSequenceOid(Oid relationId, AttrNumber attnum);
 
 
 /* truncate.c - forward declarations */
diff --git a/src/include/distributed/coordinator_protocol.h b/src/include/distributed/coordinator_protocol.h
index 07f8e84d6..3c9bf8ad6 100644
--- a/src/include/distributed/coordinator_protocol.h
+++ b/src/include/distributed/coordinator_protocol.h
@@ -111,6 +111,25 @@ typedef enum IndexDefinitionDeparseFlags
 } IndexDefinitionDeparseFlags;
 
 
+/*
+ * IncludeSequenceDefaults decides on inclusion of DEFAULT clauses for columns
+ * getting their default values from a sequence when creating the definition
+ * of a table.
+ */
+typedef enum IncludeSequenceDefaults
+{
+	NO_SEQUENCE_DEFAULTS = 0, /* don't include sequence defaults */
+	NEXTVAL_SEQUENCE_DEFAULTS = 1, /* include sequence defaults */
+
+	/*
+	 * Include sequence defaults, but use worker_nextval instead of nextval
+	 * when the default will be called in worker node, and the column type is
+	 * int or smallint.
+	 */
+	WORKER_NEXTVAL_SEQUENCE_DEFAULTS = 2,
+} IncludeSequenceDefaults;
+
+
 struct TableDDLCommand;
 typedef struct TableDDLCommand TableDDLCommand;
 typedef char *(*TableDDLFunction)(void *context);
@@ -193,11 +212,12 @@ extern bool CStoreTable(Oid relationId);
 extern uint64 GetNextShardId(void);
 extern uint64 GetNextPlacementId(void);
 extern Oid ResolveRelationId(text *relationName, bool missingOk);
-extern List * GetFullTableCreationCommands(Oid relationId, bool includeSequenceDefaults);
+extern List * GetFullTableCreationCommands(Oid relationId,
+										   IncludeSequenceDefaults includeSequenceDefaults);
 extern List * GetPostLoadTableCreationCommands(Oid relationId, bool includeIndexes,
 											   bool includeReplicaIdentity);
-extern List * GetPreLoadTableCreationCommands(Oid relationId,
-											  bool includeSequenceDefaults,
+extern List * GetPreLoadTableCreationCommands(Oid relationId, IncludeSequenceDefaults
+											  includeSequenceDefaults,
 											  char *accessMethod);
 extern List * GetTableIndexAndConstraintCommands(Oid relationId, int indexFlags);
 extern List * GetTableIndexAndConstraintCommandsExcludingReplicaIdentity(Oid relationId,
diff --git a/src/include/distributed/worker_protocol.h b/src/include/distributed/worker_protocol.h
index b91d64184..5b950084f 100644
--- a/src/include/distributed/worker_protocol.h
+++ b/src/include/distributed/worker_protocol.h
@@ -162,5 +162,7 @@ extern Datum worker_find_block_local_path(PG_FUNCTION_ARGS);
 /* Function declaration for calculating hashed value */
 extern Datum worker_hash(PG_FUNCTION_ARGS);
 
+/* Function declaration for calculating nextval() in worker */
+extern Datum worker_nextval(PG_FUNCTION_ARGS);
 
 #endif   /* WORKER_PROTOCOL_H */
diff --git a/src/test/regress/expected/multi_extension.out b/src/test/regress/expected/multi_extension.out
index d4e37b787..0a6ca29a6 100644
--- a/src/test/regress/expected/multi_extension.out
+++ b/src/test/regress/expected/multi_extension.out
@@ -810,7 +810,8 @@ SELECT * FROM multi_extension.print_extension_changes();
                                                             | function drop_old_time_partitions(regclass,timestamp with time zone)
                                                             | function get_missing_time_partition_ranges(regclass,interval,timestamp with time zone,timestamp with time zone) TABLE(partition_name text, range_from_value text, range_to_value text)
                                                             | function stop_metadata_sync_to_node(text,integer,boolean) void
-(15 rows)
+                                                            | function worker_nextval(regclass) integer
+(16 rows)
 
 DROP TABLE multi_extension.prev_objects, multi_extension.extension_diff;
 -- show running version
diff --git a/src/test/regress/expected/multi_metadata_sync.out b/src/test/regress/expected/multi_metadata_sync.out
index 97d5f1c9d..ad0369790 100644
--- a/src/test/regress/expected/multi_metadata_sync.out
+++ b/src/test/regress/expected/multi_metadata_sync.out
@@ -985,7 +985,9 @@ SELECT create_distributed_table('mx_table_with_small_sequence', 'a');
 
 INSERT INTO mx_table_with_small_sequence VALUES (0);
 \c - - - :worker_1_port
+-- Insert doesn't work because the defaults are of type int and smallint
 INSERT INTO mx_table_with_small_sequence VALUES (1), (3);
+ERROR:  nextval(sequence) calls in worker nodes are not supported for column defaults of type int or smallint
 \c - - - :master_port
 SET citus.shard_replication_factor TO 1;
 -- Create an MX table with (BIGSERIAL) sequences
@@ -996,6 +998,7 @@ SELECT create_distributed_table('mx_table_with_sequence', 'a');
 
 (1 row)
 
+INSERT INTO mx_table_with_sequence VALUES (0);
 SELECT "Column", "Type", "Modifiers" FROM table_desc WHERE relid='mx_table_with_sequence'::regclass;
  Column |  Type   |                             Modifiers
 ---------------------------------------------------------------------
@@ -1042,6 +1045,8 @@ SELECT "Column", "Type", "Modifiers" FROM table_desc WHERE relid='mx_table_with_
  public | mx_table_with_sequence_c_seq | sequence | postgres
 (1 row)
 
+-- Insert works because the defaults are of type bigint
+INSERT INTO mx_table_with_sequence VALUES (1), (3);
 -- check that pg_depend records exist on the worker
 SELECT refobjsubid FROM pg_depend
 WHERE objid = 'mx_table_with_sequence_b_seq'::regclass AND refobjid = 'mx_table_with_sequence'::regclass;
@@ -1061,13 +1066,13 @@ WHERE objid = 'mx_table_with_sequence_c_seq'::regclass AND refobjid = 'mx_table_
 SELECT nextval('mx_table_with_sequence_b_seq');
      nextval
 ---------------------------------------------------------------------
- 281474976710657
+ 281474976710659
 (1 row)
 
 SELECT nextval('mx_table_with_sequence_c_seq');
      nextval
 ---------------------------------------------------------------------
- 281474976710657
+ 281474976710659
 (1 row)
 
 -- Check that adding a new metadata node sets the sequence space correctly
@@ -1119,7 +1124,11 @@ SELECT nextval('mx_table_with_sequence_c_seq');
  562949953421313
 (1 row)
 
+-- Insert doesn't work because the defaults are of type int and smallint
 INSERT INTO mx_table_with_small_sequence VALUES (2), (4);
+ERROR:  nextval(sequence) calls in worker nodes are not supported for column defaults of type int or smallint
+-- Insert works because the defaults are of type bigint
+INSERT INTO mx_table_with_sequence VALUES (2), (4);
 -- Check that dropping the mx table with sequences works as expected
 \c - - - :master_port
 -- check our small sequence values
@@ -1127,10 +1136,17 @@ SELECT a, b, c FROM mx_table_with_small_sequence ORDER BY a,b,c;
  a |     b     |  c
 ---------------------------------------------------------------------
  0 |         1 |    1
- 1 | 268435457 | 4097
- 2 | 536870913 | 8193
- 3 | 268435458 | 4098
- 4 | 536870914 | 8194
+(1 row)
+
+--check our bigint sequence values
+SELECT a, b, c FROM mx_table_with_sequence ORDER BY a,b,c;
+ a |        b        |        c
+---------------------------------------------------------------------
+ 0 |               1 |               1
+ 1 | 281474976710657 | 281474976710657
+ 2 | 562949953421314 | 562949953421314
+ 3 | 281474976710658 | 281474976710658
+ 4 | 562949953421315 | 562949953421315
 (5 rows)
 
 -- Check that dropping the mx table with sequences works as expected
@@ -1672,7 +1688,7 @@ SELECT unnest(master_metadata_snapshot()) order by 1;
  CREATE TABLE mx_testing_schema.mx_test_table (col_1 integer, col_2 text NOT NULL, col_3 bigint DEFAULT nextval('mx_testing_schema.mx_test_table_col_3_seq'::regclass) NOT NULL, col_4 bigint DEFAULT nextval('public.user_defined_seq'::regclass))
  CREATE TABLE public.dist_table_1 (a integer)
  CREATE TABLE public.mx_ref (col_1 integer, col_2 text)
- CREATE TABLE public.test_table (id integer DEFAULT nextval('public.mx_test_sequence_0'::regclass), id2 integer DEFAULT nextval('public.mx_test_sequence_1'::regclass))
+ CREATE TABLE public.test_table (id integer DEFAULT worker_nextval('public.mx_test_sequence_0'::regclass), id2 integer DEFAULT worker_nextval('public.mx_test_sequence_1'::regclass))
  INSERT INTO pg_dist_node (nodeid, groupid, nodename, nodeport, noderack, hasmetadata, metadatasynced, isactive, noderole, nodecluster, shouldhaveshards) VALUES (4, 1, 'localhost', 8888, 'default', FALSE, FALSE, TRUE, 'secondary'::noderole, 'default', TRUE),(5, 1, 'localhost', 8889, 'default', FALSE, FALSE, TRUE, 'secondary'::noderole, 'second-cluster', TRUE),(1, 1, 'localhost', 57637, 'default', TRUE, TRUE, TRUE, 'primary'::noderole, 'default', TRUE),(7, 5, 'localhost', 57638, 'default', TRUE, TRUE, TRUE, 'primary'::noderole, 'default', TRUE)
  SELECT citus_internal_add_partition_metadata ('mx_test_schema_1.mx_table_1'::regclass, 'h', 'col1', 3, 's')
  SELECT citus_internal_add_partition_metadata ('mx_test_schema_2.mx_table_2'::regclass, 'h', 'col1', 3, 's')
diff --git a/src/test/regress/expected/multi_sequence_default.out b/src/test/regress/expected/multi_sequence_default.out
index 9ed0b0baf..903feaeeb 100644
--- a/src/test/regress/expected/multi_sequence_default.out
+++ b/src/test/regress/expected/multi_sequence_default.out
@@ -184,7 +184,7 @@ SELECT create_distributed_table('seq_test_4','x');
 (1 row)
 
 CREATE SEQUENCE seq_4;
-ALTER TABLE seq_test_4 ADD COLUMN a int DEFAULT nextval('seq_4');
+ALTER TABLE seq_test_4 ADD COLUMN a bigint DEFAULT nextval('seq_4');
 SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
  start_metadata_sync_to_node
 ---------------------------------------------------------------------
@@ -195,28 +195,21 @@ DROP SEQUENCE seq_4 CASCADE;
 NOTICE:  drop cascades to default value for column a of table seq_test_4
 TRUNCATE seq_test_4;
 CREATE SEQUENCE seq_4;
-ALTER TABLE seq_test_4 ADD COLUMN b int DEFAULT nextval('seq_4');
+ALTER TABLE seq_test_4 ADD COLUMN b bigint DEFAULT nextval('seq_4');
 -- on worker it should generate high sequence number
 \c - - - :worker_1_port
 INSERT INTO sequence_default.seq_test_4 VALUES (1,2) RETURNING *;
- x | y | a |     b
+ x | y | a |        b
 ---------------------------------------------------------------------
- 1 | 2 |   | 268435457
+ 1 | 2 |   | 281474976710657
 (1 row)
 
--- check that we have can properly insert to tables from before metadata sync
+-- check that we have can't insert to tables from before metadata sync
+-- seq_test_0 and seq_test_0_local_table have int and smallint column defaults
 INSERT INTO sequence_default.seq_test_0 VALUES (1,2) RETURNING *;
- x | y |     z     | w00  | w01  |    w10    |    w11    |       w20       |       w21
----------------------------------------------------------------------
- 1 | 2 | 268435457 | 4097 | 4097 | 268435457 | 268435457 | 281474976710657 | 281474976710657
-(1 row)
-
+ERROR:  nextval(sequence) calls in worker nodes are not supported for column defaults of type int or smallint
 INSERT INTO sequence_default.seq_test_0_local_table VALUES (1,2) RETURNING *;
- x | y |     z     | w00  | w01  |    w10    |    w11    |       w20       |       w21
----------------------------------------------------------------------
- 1 | 2 | 268435457 | 4097 | 4097 | 268435457 | 268435457 | 281474976710657 | 281474976710657
-(1 row)
-
+ERROR:  nextval(sequence) calls in worker nodes are not supported for column defaults of type int or smallint
 \c - - - :master_port
 SET citus.shard_replication_factor TO 1;
 SET search_path = sequence_default, public;
@@ -250,14 +243,10 @@ ALTER TABLE seq_test_1 ADD COLUMN z int DEFAULT nextval('seq_1');
 ---------------------------------------------------------------------
  integer |     1 |       1 | 2147483647 |         1 | no      |     1
 
--- check insertion is within int bounds in the worker
+-- check insertion doesn't work in the worker because type is int
 \c - - - :worker_1_port
 INSERT INTO sequence_default.seq_test_1 values (1, 2) RETURNING *;
- x | y |     z
----------------------------------------------------------------------
- 1 | 2 | 268435457
-(1 row)
-
+ERROR:  nextval(sequence) calls in worker nodes are not supported for column defaults of type int or smallint
 \c - - - :master_port
 SET citus.shard_replication_factor TO 1;
 SET search_path = sequence_default, public;
@@ -291,14 +280,10 @@ ALTER TABLE seq_test_1_local_table ADD COLUMN z int DEFAULT nextval('seq_1_local
 ---------------------------------------------------------------------
  integer |     1 |       1 | 2147483647 |         1 | no      |     1
 
--- check insertion is within int bounds in the worker
+-- check insertion doesn't work in the worker because type is int
 \c - - - :worker_1_port
 INSERT INTO sequence_default.seq_test_1_local_table values (1, 2) RETURNING *;
- x | y |     z
----------------------------------------------------------------------
- 1 | 2 | 268435457
-(1 row)
-
+ERROR:  nextval(sequence) calls in worker nodes are not supported for column defaults of type int or smallint
 \c - - - :master_port
 SET citus.shard_replication_factor TO 1;
 SET search_path = sequence_default, public;
@@ -436,7 +421,7 @@ SELECT create_distributed_table('seq_test_5','x');
 
 CREATE SCHEMA sequence_default_1;
 CREATE SEQUENCE sequence_default_1.seq_5;
-ALTER TABLE seq_test_5 ADD COLUMN a int DEFAULT nextval('sequence_default_1.seq_5');
+ALTER TABLE seq_test_5 ADD COLUMN a bigint DEFAULT nextval('sequence_default_1.seq_5');
 DROP SCHEMA sequence_default_1 CASCADE;
 NOTICE:  drop cascades to 2 other objects
 DETAIL:  drop cascades to sequence sequence_default_1.seq_5
@@ -451,9 +436,9 @@ INSERT INTO seq_test_5 VALUES (1, 2) RETURNING *;
 -- but is still present on worker
 \c - - - :worker_1_port
 INSERT INTO sequence_default.seq_test_5 VALUES (1, 2) RETURNING *;
- x | y |     a
+ x | y |        a
 ---------------------------------------------------------------------
- 1 | 2 | 268435457
+ 1 | 2 | 281474976710657
 (1 row)
 
 \c - - - :master_port
@@ -593,10 +578,10 @@ ERROR:  cannot alter OWNED BY option of a sequence already owned by a distribute
 ALTER SEQUENCE seq_8 SET SCHEMA sequence_default_8;
 \c - - - :worker_1_port
 \d sequence_default_8.seq_8
-                    Sequence "sequence_default_8.seq_8"
-  Type   |   Start   |  Minimum  |  Maximum  | Increment | Cycles? | Cache
+                 Sequence "sequence_default_8.seq_8"
+  Type   | Start | Minimum |  Maximum   | Increment | Cycles? | Cache
 ---------------------------------------------------------------------
- integer | 268435457 | 268435457 | 536870913 |         3 | yes     |    10
+ integer |     1 |       1 | 2147483647 |         3 | yes     |    10
 
 \c - - - :master_port
 SET citus.shard_replication_factor TO 1;
@@ -611,10 +596,10 @@ SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
 ALTER TABLE sequence_default_8.seq_8 SET SCHEMA sequence_default;
 \c - - - :worker_1_port
 \d sequence_default.seq_8
-                     Sequence "sequence_default.seq_8"
-  Type   |   Start   |  Minimum  |  Maximum  | Increment | Cycles? | Cache
+                  Sequence "sequence_default.seq_8"
+  Type   | Start | Minimum |  Maximum   | Increment | Cycles? | Cache
 ---------------------------------------------------------------------
- integer | 268435457 | 268435457 | 536870913 |         3 | yes     |    10
+ integer |     1 |       1 | 2147483647 |         3 | yes     |    10
 
 \c - - - :master_port
 SET citus.shard_replication_factor TO 1;
@@ -638,9 +623,9 @@ CREATE SEQUENCE seq_9;
 CREATE SEQUENCE seq_10;
 CREATE TABLE seq_test_9 (x int, y int DEFAULT nextval('seq_9') - nextval('seq_10'));
 SELECT create_distributed_table('seq_test_9', 'x');
-ERROR:  More than one sequence in a column default is not supported for distribution
+ERROR:  More than one sequence in a column default is not supported for distribution or for adding local tables to metadata
 SELECT citus_add_local_table_to_metadata('seq_test_9');
-ERROR:  More than one sequence in a column default is not supported for adding local tables to metadata
+ERROR:  More than one sequence in a column default is not supported for distribution or for adding local tables to metadata
 ALTER TABLE seq_test_9 ALTER COLUMN y SET DEFAULT nextval('seq_9');
 SELECT create_distributed_table('seq_test_9', 'x');
  create_distributed_table
@@ -772,6 +757,200 @@ SELECT create_distributed_table('seq_test_11', 'col1');
 INSERT INTO sequence_default.seq_test_10 VALUES (1);
 ERROR:  relation "seq_11" does not exist
 \c - - - :master_port
+SET citus.shard_replication_factor TO 1;
+SET search_path = sequence_default, public;
+SELECT stop_metadata_sync_to_node('localhost', :worker_1_port);
+NOTICE:  dropping metadata on the node (localhost,57637)
+ stop_metadata_sync_to_node
+---------------------------------------------------------------------
+
+(1 row)
+
+-- Check worker_nextval and setval precautions for int and smallint column defaults
+-- For details see issue #5126 and PR #5254
+-- https://github.com/citusdata/citus/issues/5126
+CREATE SEQUENCE seq_12;
+CREATE SEQUENCE seq_13;
+CREATE SEQUENCE seq_14;
+CREATE TABLE seq_test_12(col0 text, col1 smallint DEFAULT nextval('seq_12'),
+                         col2 int DEFAULT nextval('seq_13'),
+                         col3 bigint DEFAULT nextval('seq_14'));
+SELECT create_distributed_table('seq_test_12', 'col0');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
+ start_metadata_sync_to_node
+---------------------------------------------------------------------
+
+(1 row)
+
+INSERT INTO seq_test_12 VALUES ('hello0') RETURNING *;
+  col0  | col1 | col2 | col3
+---------------------------------------------------------------------
+ hello0 |    1 |    1 |    1
+(1 row)
+
+\c - - - :worker_1_port
+SET search_path = sequence_default, public;
+-- we should see worker_nextval for int and smallint columns
+SELECT table_name, column_name, data_type, column_default FROM information_schema.columns
+WHERE table_name = 'seq_test_12' ORDER BY column_name;
+ table_name  | column_name | data_type |           column_default
+---------------------------------------------------------------------
+ seq_test_12 | col0        | text      |
+ seq_test_12 | col1        | smallint  | worker_nextval('seq_12'::regclass)
+ seq_test_12 | col2        | integer   | worker_nextval('seq_13'::regclass)
+ seq_test_12 | col3        | bigint    | nextval('seq_14'::regclass)
+(4 rows)
+
+-- insertion from worker should fail
+INSERT INTO seq_test_12 VALUES ('hello1') RETURNING *;
+ERROR:  nextval(sequence) calls in worker nodes are not supported for column defaults of type int or smallint
+-- nextval from worker should fail for int and smallint sequences
+SELECT nextval('seq_12');
+ERROR:  nextval: reached maximum value of sequence "seq_12" (32767)
+SELECT nextval('seq_13');
+ERROR:  nextval: reached maximum value of sequence "seq_13" (2147483647)
+-- nextval from worker should work for bigint sequences
+SELECT nextval('seq_14');
+     nextval
+---------------------------------------------------------------------
+ 281474976710657
+(1 row)
+
+\c - - - :master_port
+SET citus.shard_replication_factor TO 1;
+SET search_path = sequence_default, public;
+SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
+ start_metadata_sync_to_node
+---------------------------------------------------------------------
+
+(1 row)
+
+TRUNCATE seq_test_12;
+ALTER TABLE seq_test_12 DROP COLUMN col1;
+ALTER TABLE seq_test_12 DROP COLUMN col2;
+ALTER TABLE seq_test_12 DROP COLUMN col3;
+DROP SEQUENCE seq_12, seq_13, seq_14;
+CREATE SEQUENCE seq_12;
+CREATE SEQUENCE seq_13;
+CREATE SEQUENCE seq_14;
+ALTER TABLE seq_test_12 ADD COLUMN col1 smallint DEFAULT nextval('seq_14');
+ALTER TABLE seq_test_12 ADD COLUMN col2 int DEFAULT nextval('seq_13');
+ALTER TABLE seq_test_12 ADD COLUMN col3 bigint DEFAULT nextval('seq_12');
+ALTER TABLE seq_test_12 ADD COLUMN col4 smallint;
+ALTER TABLE seq_test_12 ALTER COLUMN col4 SET DEFAULT nextval('seq_14');
+ALTER TABLE seq_test_12 ADD COLUMN col5 int;
+ALTER TABLE seq_test_12 ALTER COLUMN col5 SET DEFAULT nextval('seq_13');
+ALTER TABLE seq_test_12 ADD COLUMN col6 bigint;
+ALTER TABLE seq_test_12 ALTER COLUMN col6 SET DEFAULT nextval('seq_12');
+INSERT INTO seq_test_12 VALUES ('hello1') RETURNING *;
+  col0  | col1 | col2 | col3 | col4 | col5 | col6
+---------------------------------------------------------------------
+ hello1 |    1 |    1 |    1 |    2 |    2 |    2
+(1 row)
+
+\c - - - :worker_1_port
+SET search_path = sequence_default, public;
+-- we should see worker_nextval for int and smallint columns
+SELECT table_name, column_name, data_type, column_default FROM information_schema.columns
+WHERE table_name = 'seq_test_12' ORDER BY column_name;
+ table_name  | column_name | data_type |           column_default
+---------------------------------------------------------------------
+ seq_test_12 | col0        | text      |
+ seq_test_12 | col1        | smallint  | worker_nextval('seq_14'::regclass)
+ seq_test_12 | col2        | integer   | worker_nextval('seq_13'::regclass)
+ seq_test_12 | col3        | bigint    | nextval('seq_12'::regclass)
+ seq_test_12 | col4        | smallint  | worker_nextval('seq_14'::regclass)
+ seq_test_12 | col5        | integer   | worker_nextval('seq_13'::regclass)
+ seq_test_12 | col6        | bigint    | nextval('seq_12'::regclass)
+(7 rows)
+
+-- insertion from worker should fail
+INSERT INTO seq_test_12 VALUES ('hello2') RETURNING *;
+ERROR:  nextval(sequence) calls in worker nodes are not supported for column defaults of type int or smallint
+-- nextval from worker should work for bigint sequences
+SELECT nextval('seq_12');
+     nextval
+---------------------------------------------------------------------
+ 281474976710657
+(1 row)
+
+-- nextval from worker should fail for int and smallint sequences
+SELECT nextval('seq_13');
+ERROR:  nextval: reached maximum value of sequence "seq_13" (2147483647)
+SELECT nextval('seq_14');
+ERROR:  nextval: reached maximum value of sequence "seq_14" (32767)
+\c - - - :master_port
+SET citus.shard_replication_factor TO 1;
+SET search_path = sequence_default, public;
+SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
+ start_metadata_sync_to_node
+---------------------------------------------------------------------
+
+(1 row)
+
+SELECT undistribute_table('seq_test_12');
+NOTICE:  creating a new table for sequence_default.seq_test_12
+NOTICE:  moving the data of sequence_default.seq_test_12
+NOTICE:  dropping the old sequence_default.seq_test_12
+NOTICE:  renaming the new table to sequence_default.seq_test_12
+ undistribute_table
+---------------------------------------------------------------------
+
+(1 row)
+
+SELECT create_distributed_table('seq_test_12', 'col0');
+NOTICE:  Copying data from local table...
+NOTICE:  copying the data has completed
+DETAIL:  The local data in the table is no longer visible, but is still on disk.
+HINT:  To remove the local data, run: SELECT truncate_local_data_after_distributing_table($$sequence_default.seq_test_12$$)
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+INSERT INTO seq_test_12 VALUES ('hello2') RETURNING *;
+  col0  | col1 | col2 | col3 | col4 | col5 | col6
+---------------------------------------------------------------------
+ hello2 |    3 |    3 |    3 |    4 |    4 |    4
+(1 row)
+
+\c - - - :worker_1_port
+SET search_path = sequence_default, public;
+-- we should see worker_nextval for int and smallint columns
+SELECT table_name, column_name, data_type, column_default FROM information_schema.columns
+WHERE table_name = 'seq_test_12' ORDER BY column_name;
+ table_name  | column_name | data_type |           column_default
+---------------------------------------------------------------------
+ seq_test_12 | col0        | text      |
+ seq_test_12 | col1        | smallint  | worker_nextval('seq_14'::regclass)
+ seq_test_12 | col2        | integer   | worker_nextval('seq_13'::regclass)
+ seq_test_12 | col3        | bigint    | nextval('seq_12'::regclass)
+ seq_test_12 | col4        | smallint  | worker_nextval('seq_14'::regclass)
+ seq_test_12 | col5        | integer   | worker_nextval('seq_13'::regclass)
+ seq_test_12 | col6        | bigint    | nextval('seq_12'::regclass)
+(7 rows)
+
+-- insertion from worker should fail
+INSERT INTO seq_test_12 VALUES ('hello2') RETURNING *;
+ERROR:  nextval(sequence) calls in worker nodes are not supported for column defaults of type int or smallint
+-- nextval from worker should work for bigint sequences
+SELECT nextval('seq_12');
+     nextval
+---------------------------------------------------------------------
+ 281474976710658
+(1 row)
+
+-- nextval from worker should fail for int and smallint sequences
+SELECT nextval('seq_13');
+ERROR:  nextval: reached maximum value of sequence "seq_13" (2147483647)
+SELECT nextval('seq_14');
+ERROR:  nextval: reached maximum value of sequence "seq_14" (32767)
+\c - - - :master_port
 -- clean up
 DROP TABLE sequence_default.seq_test_7_par;
 SET client_min_messages TO error; -- suppress cascading objects dropping
diff --git a/src/test/regress/expected/upgrade_list_citus_objects.out b/src/test/regress/expected/upgrade_list_citus_objects.out
index 9f48ba9e6..bb2efb550 100644
--- a/src/test/regress/expected/upgrade_list_citus_objects.out
+++ b/src/test/regress/expected/upgrade_list_citus_objects.out
@@ -207,6 +207,7 @@ ORDER BY 1;
  function worker_hash_partition_table(bigint,integer,text,text,oid,anyarray)
  function worker_last_saved_explain_analyze()
  function worker_merge_files_into_table(bigint,integer,text[],text[])
+ function worker_nextval(regclass)
  function worker_partial_agg(oid,anyelement)
  function worker_partial_agg_ffunc(internal)
  function worker_partial_agg_sfunc(internal,oid,anyelement)
@@ -257,5 +258,5 @@ ORDER BY 1;
  view citus_worker_stat_activity
  view pg_dist_shard_placement
  view time_partitions
-(241 rows)
+(242 rows)
 
diff --git a/src/test/regress/sql/multi_metadata_sync.sql b/src/test/regress/sql/multi_metadata_sync.sql
index ab5247dd4..a1e69b2a3 100644
--- a/src/test/regress/sql/multi_metadata_sync.sql
+++ b/src/test/regress/sql/multi_metadata_sync.sql
@@ -452,6 +452,7 @@ SELECT create_distributed_table('mx_table_with_small_sequence', 'a');
 INSERT INTO mx_table_with_small_sequence VALUES (0);
 
 \c - - - :worker_1_port
+-- Insert doesn't work because the defaults are of type int and smallint
 INSERT INTO mx_table_with_small_sequence VALUES (1), (3);
 
 \c - - - :master_port
@@ -460,6 +461,7 @@ SET citus.shard_replication_factor TO 1;
 -- Create an MX table with (BIGSERIAL) sequences
 CREATE TABLE mx_table_with_sequence(a int, b BIGSERIAL, c BIGSERIAL);
 SELECT create_distributed_table('mx_table_with_sequence', 'a');
+INSERT INTO mx_table_with_sequence VALUES (0);
 SELECT "Column", "Type", "Modifiers" FROM table_desc WHERE relid='mx_table_with_sequence'::regclass;
 \ds mx_table_with_sequence_b_seq
 \ds mx_table_with_sequence_c_seq
@@ -470,6 +472,9 @@ SELECT "Column", "Type", "Modifiers" FROM table_desc WHERE relid='mx_table_with_
 \ds mx_table_with_sequence_b_seq
 \ds mx_table_with_sequence_c_seq
 
+-- Insert works because the defaults are of type bigint
+INSERT INTO mx_table_with_sequence VALUES (1), (3);
+
 -- check that pg_depend records exist on the worker
 SELECT refobjsubid FROM pg_depend
 WHERE objid = 'mx_table_with_sequence_b_seq'::regclass AND refobjid = 'mx_table_with_sequence'::regclass;
@@ -493,7 +498,10 @@ SELECT "Column", "Type", "Modifiers" FROM table_desc WHERE relid='mx_table_with_
 SELECT nextval('mx_table_with_sequence_b_seq');
 SELECT nextval('mx_table_with_sequence_c_seq');
 
+-- Insert doesn't work because the defaults are of type int and smallint
 INSERT INTO mx_table_with_small_sequence VALUES (2), (4);
+-- Insert works because the defaults are of type bigint
+INSERT INTO mx_table_with_sequence VALUES (2), (4);
 
 -- Check that dropping the mx table with sequences works as expected
 \c - - - :master_port
@@ -501,6 +509,9 @@ INSERT INTO mx_table_with_small_sequence VALUES (2), (4);
 -- check our small sequence values
 SELECT a, b, c FROM mx_table_with_small_sequence ORDER BY a,b,c;
 
+--check our bigint sequence values
+SELECT a, b, c FROM mx_table_with_sequence ORDER BY a,b,c;
+
 -- Check that dropping the mx table with sequences works as expected
 DROP TABLE mx_table_with_small_sequence, mx_table_with_sequence;
 \d mx_table_with_sequence
diff --git a/src/test/regress/sql/multi_sequence_default.sql b/src/test/regress/sql/multi_sequence_default.sql
index 405ffac37..4b0ac1ca3 100644
--- a/src/test/regress/sql/multi_sequence_default.sql
+++ b/src/test/regress/sql/multi_sequence_default.sql
@@ -90,17 +90,18 @@ ALTER TABLE seq_test_0_local_table ALTER COLUMN z TYPE smallint;
 CREATE TABLE seq_test_4 (x int, y int);
 SELECT create_distributed_table('seq_test_4','x');
 CREATE SEQUENCE seq_4;
-ALTER TABLE seq_test_4 ADD COLUMN a int DEFAULT nextval('seq_4');
+ALTER TABLE seq_test_4 ADD COLUMN a bigint DEFAULT nextval('seq_4');
 SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
 DROP SEQUENCE seq_4 CASCADE;
 TRUNCATE seq_test_4;
 CREATE SEQUENCE seq_4;
-ALTER TABLE seq_test_4 ADD COLUMN b int DEFAULT nextval('seq_4');
+ALTER TABLE seq_test_4 ADD COLUMN b bigint DEFAULT nextval('seq_4');
 -- on worker it should generate high sequence number
 \c - - - :worker_1_port
 INSERT INTO sequence_default.seq_test_4 VALUES (1,2) RETURNING *;
 
--- check that we have can properly insert to tables from before metadata sync
+-- check that we have can't insert to tables from before metadata sync
+-- seq_test_0 and seq_test_0_local_table have int and smallint column defaults
 INSERT INTO sequence_default.seq_test_0 VALUES (1,2) RETURNING *;
 INSERT INTO sequence_default.seq_test_0_local_table VALUES (1,2) RETURNING *;
 
@@ -119,7 +120,7 @@ SELECT create_distributed_table('seq_test_1','x');
 ALTER TABLE seq_test_1 ADD COLUMN z int DEFAULT nextval('seq_1');
 -- type is changed to int
 \d seq_1
--- check insertion is within int bounds in the worker
+-- check insertion doesn't work in the worker because type is int
 \c - - - :worker_1_port
 INSERT INTO sequence_default.seq_test_1 values (1, 2) RETURNING *;
 \c - - - :master_port
@@ -137,7 +138,7 @@ SELECT citus_add_local_table_to_metadata('seq_test_1_local_table');
 ALTER TABLE seq_test_1_local_table ADD COLUMN z int DEFAULT nextval('seq_1_local_table');
 -- type is changed to int
 \d seq_1_local_table
--- check insertion is within int bounds in the worker
+-- check insertion doesn't work in the worker because type is int
 \c - - - :worker_1_port
 INSERT INTO sequence_default.seq_test_1_local_table values (1, 2) RETURNING *;
 \c - - - :master_port
@@ -218,7 +219,7 @@ CREATE TABLE seq_test_5 (x int, y int);
 SELECT create_distributed_table('seq_test_5','x');
 CREATE SCHEMA sequence_default_1;
 CREATE SEQUENCE sequence_default_1.seq_5;
-ALTER TABLE seq_test_5 ADD COLUMN a int DEFAULT nextval('sequence_default_1.seq_5');
+ALTER TABLE seq_test_5 ADD COLUMN a bigint DEFAULT nextval('sequence_default_1.seq_5');
 DROP SCHEMA sequence_default_1 CASCADE;
 -- sequence is gone from coordinator
 INSERT INTO seq_test_5 VALUES (1, 2) RETURNING *;
@@ -372,8 +373,96 @@ SELECT create_distributed_table('seq_test_11', 'col1');
 \c - - - :worker_1_port
 INSERT INTO sequence_default.seq_test_10 VALUES (1);
 \c - - - :master_port
+SET citus.shard_replication_factor TO 1;
+SET search_path = sequence_default, public;
+SELECT stop_metadata_sync_to_node('localhost', :worker_1_port);
 
 
+-- Check worker_nextval and setval precautions for int and smallint column defaults
+-- For details see issue #5126 and PR #5254
+-- https://github.com/citusdata/citus/issues/5126
+CREATE SEQUENCE seq_12;
+CREATE SEQUENCE seq_13;
+CREATE SEQUENCE seq_14;
+CREATE TABLE seq_test_12(col0 text, col1 smallint DEFAULT nextval('seq_12'),
+                         col2 int DEFAULT nextval('seq_13'),
+                         col3 bigint DEFAULT nextval('seq_14'));
+SELECT create_distributed_table('seq_test_12', 'col0');
+SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
+INSERT INTO seq_test_12 VALUES ('hello0') RETURNING *;
+
+\c - - - :worker_1_port
+SET search_path = sequence_default, public;
+-- we should see worker_nextval for int and smallint columns
+SELECT table_name, column_name, data_type, column_default FROM information_schema.columns
+WHERE table_name = 'seq_test_12' ORDER BY column_name;
+-- insertion from worker should fail
+INSERT INTO seq_test_12 VALUES ('hello1') RETURNING *;
+-- nextval from worker should fail for int and smallint sequences
+SELECT nextval('seq_12');
+SELECT nextval('seq_13');
+-- nextval from worker should work for bigint sequences
+SELECT nextval('seq_14');
+
+\c - - - :master_port
+SET citus.shard_replication_factor TO 1;
+SET search_path = sequence_default, public;
+SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
+TRUNCATE seq_test_12;
+ALTER TABLE seq_test_12 DROP COLUMN col1;
+ALTER TABLE seq_test_12 DROP COLUMN col2;
+ALTER TABLE seq_test_12 DROP COLUMN col3;
+DROP SEQUENCE seq_12, seq_13, seq_14;
+CREATE SEQUENCE seq_12;
+CREATE SEQUENCE seq_13;
+CREATE SEQUENCE seq_14;
+ALTER TABLE seq_test_12 ADD COLUMN col1 smallint DEFAULT nextval('seq_14');
+ALTER TABLE seq_test_12 ADD COLUMN col2 int DEFAULT nextval('seq_13');
+ALTER TABLE seq_test_12 ADD COLUMN col3 bigint DEFAULT nextval('seq_12');
+ALTER TABLE seq_test_12 ADD COLUMN col4 smallint;
+ALTER TABLE seq_test_12 ALTER COLUMN col4 SET DEFAULT nextval('seq_14');
+ALTER TABLE seq_test_12 ADD COLUMN col5 int;
+ALTER TABLE seq_test_12 ALTER COLUMN col5 SET DEFAULT nextval('seq_13');
+ALTER TABLE seq_test_12 ADD COLUMN col6 bigint;
+ALTER TABLE seq_test_12 ALTER COLUMN col6 SET DEFAULT nextval('seq_12');
+INSERT INTO seq_test_12 VALUES ('hello1') RETURNING *;
+
+\c - - - :worker_1_port
+SET search_path = sequence_default, public;
+-- we should see worker_nextval for int and smallint columns
+SELECT table_name, column_name, data_type, column_default FROM information_schema.columns
+WHERE table_name = 'seq_test_12' ORDER BY column_name;
+-- insertion from worker should fail
+INSERT INTO seq_test_12 VALUES ('hello2') RETURNING *;
+-- nextval from worker should work for bigint sequences
+SELECT nextval('seq_12');
+-- nextval from worker should fail for int and smallint sequences
+SELECT nextval('seq_13');
+SELECT nextval('seq_14');
+
+\c - - - :master_port
+SET citus.shard_replication_factor TO 1;
+SET search_path = sequence_default, public;
+SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
+SELECT undistribute_table('seq_test_12');
+SELECT create_distributed_table('seq_test_12', 'col0');
+INSERT INTO seq_test_12 VALUES ('hello2') RETURNING *;
+
+\c - - - :worker_1_port
+SET search_path = sequence_default, public;
+-- we should see worker_nextval for int and smallint columns
+SELECT table_name, column_name, data_type, column_default FROM information_schema.columns
+WHERE table_name = 'seq_test_12' ORDER BY column_name;
+-- insertion from worker should fail
+INSERT INTO seq_test_12 VALUES ('hello2') RETURNING *;
+-- nextval from worker should work for bigint sequences
+SELECT nextval('seq_12');
+-- nextval from worker should fail for int and smallint sequences
+SELECT nextval('seq_13');
+SELECT nextval('seq_14');
+
+\c - - - :master_port
+
 -- clean up
 DROP TABLE sequence_default.seq_test_7_par;
 SET client_min_messages TO error; -- suppress cascading objects dropping