Address review comments

src/backend/distributed/operations/shard_split.c

@@ -63,7 +63,8 @@ static void CreateAndCopySplitShardsForShardGroup(
 static void CreateSplitShardsForShardGroup(HTAB *mapOfShardToPlacementCreatedByWorkflow,
 										   List *shardGroupSplitIntervalListList,
 										   List *workersForPlacementList);
-static void CreateDummyShardsForShardGroup(List *sourceColocatedShardIntervalList,
+static void CreateDummyShardsForShardGroup(HTAB *mapOfDummyShardToPlacement,
+										   List *sourceColocatedShardIntervalList,
 										   List *shardGroupSplitIntervalListList,
 										   WorkerNode *sourceWorkerNode,
 										   List *workersForPlacementList);
@@ -71,7 +72,8 @@ static HTAB * CreateWorkerForPlacementSet(List *workersForPlacementList);
 static void CreateAuxiliaryStructuresForShardGroup(List *shardGroupSplitIntervalListList,
 												   List *workersForPlacementList,
 												   bool includeReplicaIdentity);
-static void CreateReplicaIdentities(List *shardGroupSplitIntervalListList,
+static void CreateReplicaIdentities(HTAB *mapOfDummyShardToPlacement,
+									List *shardGroupSplitIntervalListList,
 									List *workersForPlacementList);
 static void CreateObjectOnPlacement(List *objectCreationCommandList,
 									WorkerNode *workerNode);
@@ -120,8 +122,9 @@ static List * ExecuteSplitShardReplicationSetupUDF(WorkerNode *sourceWorkerNode,
 												   List *sourceColocatedShardIntervalList,
 												   List *shardGroupSplitIntervalListList,
 												   List *destinationWorkerNodesList);
-static void AddDummyShardEntryInMap(uint32 targetNodeId, ShardInterval *shardInterval);
-static void DropDummyShards(void);
+static void AddDummyShardEntryInMap(HTAB *mapOfDummyShards, uint32 targetNodeId,
+									ShardInterval *shardInterval);
+static void DropDummyShards(HTAB *mapOfDummyShardToPlacement);
 static void DropDummyShard(MultiConnection *connection, ShardInterval *shardInterval);
 
 
@@ -137,13 +140,6 @@ static const char *const SplitTargetName[] =
 	[ISOLATE_TENANT_TO_NEW_SHARD] = "tenant",
 };
 
-/*
- * Map containing list of dummy shards created on target nodes.
- * Key - <nodeId, tableOwnerId>
- * Value - ShardInterval
- */
-static HTAB *DummyShardInfoHashMap = NULL;
-
 /* Function definitions */
 
 /*
@@ -1258,7 +1254,6 @@ NonBlockingShardSplit(SplitOperation splitOperation,
 {
 	char *superUser = CitusExtensionOwnerName();
 	char *databaseName = get_database_name(MyDatabaseId);
-	int connectionFlags = FORCE_NEW_CONNECTION;
 
 	List *sourceColocatedShardIntervalList = ColocatedShardIntervalList(
 		shardIntervalToSplit);
@@ -1279,6 +1274,7 @@ NonBlockingShardSplit(SplitOperation splitOperation,
 
 	DropAllShardSplitLeftOvers(sourceShardToCopyNode, shardSplitHashMapForPublication);
 
+	int connectionFlags = FORCE_NEW_CONNECTION;
 	MultiConnection *sourceConnection = GetNodeUserDatabaseConnection(connectionFlags,
 																	  sourceShardToCopyNode
 																	  ->
@@ -1293,6 +1289,8 @@ NonBlockingShardSplit(SplitOperation splitOperation,
 	HTAB *mapOfShardToPlacementCreatedByWorkflow =
 		CreateEmptyMapForShardsCreatedByWorkflow();
 
+	HTAB *mapOfDummyShardToPlacement = SetupHashMapForShardInfo();
+
 	/* Non-Blocking shard split workflow starts here */
 	PG_TRY();
 	{
@@ -1307,12 +1305,14 @@ NonBlockingShardSplit(SplitOperation splitOperation,
 		 *    information.
 		 */
 		CreateDummyShardsForShardGroup(
+			mapOfDummyShardToPlacement,
 			sourceColocatedShardIntervalList,
 			shardGroupSplitIntervalListList,
 			sourceShardToCopyNode,
 			workersForPlacementList);
 
-		CreateReplicaIdentities(shardGroupSplitIntervalListList, workersForPlacementList);
+		CreateReplicaIdentities(mapOfDummyShardToPlacement,
+								shardGroupSplitIntervalListList, workersForPlacementList);
 
 
 		/* 3) Create Publications. */
@@ -1426,7 +1426,7 @@ NonBlockingShardSplit(SplitOperation splitOperation,
 
 		/* 21) Drop dummy shards.
 		 * TODO(saawasek):Refactor and pass hashmap.Currently map is global variable */
-		DropDummyShards();
+		DropDummyShards(mapOfDummyShardToPlacement);
 
 
 		/* 22) Close source connection */
@@ -1447,7 +1447,7 @@ NonBlockingShardSplit(SplitOperation splitOperation,
 		DropAllShardSplitLeftOvers(sourceShardToCopyNode,
 								   shardSplitHashMapForPublication);
 
-		DropDummyShards();
+		DropDummyShards(mapOfDummyShardToPlacement);
 
 		PG_RE_THROW();
 	}
@@ -1478,17 +1478,12 @@ NonBlockingShardSplit(SplitOperation splitOperation,
  * Note 2 : Given there is an overlap of source and destination in Worker0, Shard1_1 and Shard2_1 need not be created.
  */
 static void
-CreateDummyShardsForShardGroup(List *sourceColocatedShardIntervalList,
+CreateDummyShardsForShardGroup(HTAB *mapOfDummyShardToPlacement,
+							   List *sourceColocatedShardIntervalList,
 							   List *shardGroupSplitIntervalListList,
 							   WorkerNode *sourceWorkerNode,
 							   List *workersForPlacementList)
 {
-	/*
-	 * Setup a hash map to store list of dummy shards created on nodes.
-	 * This will facilitate easy cleanup.
-	 */
-	DummyShardInfoHashMap = SetupHashMapForShardInfo();
-
 	/*
 	 * Statisfy Constraint 1: Create dummy source shard(s) on all destination nodes.
 	 * If source node is also in desintation, skip dummy shard creation(see Note 1 from function description).
@@ -1524,7 +1519,9 @@ CreateDummyShardsForShardGroup(List *sourceColocatedShardIntervalList,
 			CreateObjectOnPlacement(splitShardCreationCommandList, workerPlacementNode);
 
 			/* Add dummy source shard entry created for placement node in map */
-			AddDummyShardEntryInMap(workerPlacementNode->nodeId, shardInterval);
+			AddDummyShardEntryInMap(mapOfDummyShardToPlacement,
+									workerPlacementNode->nodeId,
+									shardInterval);
 		}
 	}
 
@@ -1557,12 +1554,16 @@ CreateDummyShardsForShardGroup(List *sourceColocatedShardIntervalList,
 			CreateObjectOnPlacement(splitShardCreationCommandList, sourceWorkerNode);
 
 			/* Add dummy split child shard entry created on source node */
-			AddDummyShardEntryInMap(sourceWorkerNode->nodeId, shardInterval);
+			AddDummyShardEntryInMap(mapOfDummyShardToPlacement, sourceWorkerNode->nodeId,
+									shardInterval);
 		}
 	}
 }
 
 
+/*
+ * CreateWorkerForPlacementSet returns a set with unique worker nodes.
+ */
 static HTAB *
 CreateWorkerForPlacementSet(List *workersForPlacementList)
 {
@@ -1813,7 +1814,8 @@ ParseReplicationSlotInfoFromResult(PGresult *result)
  * of logical replication. We cautiously delete only the dummy shards added in the DummyShardHashMap.
  */
 static void
-AddDummyShardEntryInMap(uint32 targetNodeId, ShardInterval *shardInterval)
+AddDummyShardEntryInMap(HTAB *mapOfDummyShardToPlacement, uint32 targetNodeId,
+						ShardInterval *shardInterval)
 {
 	NodeShardMappingKey key;
 	key.nodeId = targetNodeId;
@@ -1821,7 +1823,8 @@ AddDummyShardEntryInMap(uint32 targetNodeId, ShardInterval *shardInterval)
 
 	bool found = false;
 	NodeShardMappingEntry *nodeMappingEntry =
-		(NodeShardMappingEntry *) hash_search(DummyShardInfoHashMap, &key, HASH_ENTER,
+		(NodeShardMappingEntry *) hash_search(mapOfDummyShardToPlacement, &key,
+											  HASH_ENTER,
 											  &found);
 	if (!found)
 	{
@@ -1834,16 +1837,10 @@ AddDummyShardEntryInMap(uint32 targetNodeId, ShardInterval *shardInterval)
 
 
 static void
-DropDummyShards()
+DropDummyShards(HTAB *mapOfDummyShardToPlacement)
 {
-	/* Return if no dummy shards are created */
-	if (DummyShardInfoHashMap == NULL)
-	{
-		return;
-	}
-
 	HASH_SEQ_STATUS status;
-	hash_seq_init(&status, DummyShardInfoHashMap);
+	hash_seq_init(&status, mapOfDummyShardToPlacement);
 
 	NodeShardMappingEntry *entry = NULL;
 	while ((entry = (NodeShardMappingEntry *) hash_seq_search(&status)) != NULL)
@@ -1899,7 +1896,8 @@ DropDummyShard(MultiConnection *connection, ShardInterval *shardInterval)
 
 /*todo(saawasek): Add comments */
 static void
-CreateReplicaIdentities(List *shardGroupSplitIntervalListList,
+CreateReplicaIdentities(HTAB *mapOfDummyShardToPlacement,
+						List *shardGroupSplitIntervalListList,
 						List *workersForPlacementList)
 {
 	/*
@@ -1928,7 +1926,7 @@ CreateReplicaIdentities(List *shardGroupSplitIntervalListList,
 
 	/*todo: remove the global variable dummy map*/
 	HASH_SEQ_STATUS status;
-	hash_seq_init(&status, DummyShardInfoHashMap);
+	hash_seq_init(&status, mapOfDummyShardToPlacement);
 
 	NodeShardMappingEntry *entry = NULL;
 	while ((entry = (NodeShardMappingEntry *) hash_seq_search(&status)) != NULL)

src/backend/distributed/operations/worker_split_shard_replication_setup_udf.c

@@ -48,10 +48,9 @@ static ShardSplitInfo * CreateShardSplitInfo(uint64 sourceShardIdToSplit,
 											 int32 maxValue,
 											 int32 nodeId);
 static void AddShardSplitInfoEntryForNodeInMap(ShardSplitInfo *shardSplitInfo);
-static void PopulateShardSplitInfoInSM(ShardSplitInfoSMHeader *shardSplitInfoSMHeader,
-									   HTAB *shardInfoHashMap);
+static void PopulateShardSplitInfoInSM(ShardSplitInfoSMHeader *shardSplitInfoSMHeader);
 
-static void ReturnReplicationSlotInfo(HTAB *shardInfoHashMap, Tuplestorestate *tupleStore,
+static void ReturnReplicationSlotInfo(Tuplestorestate *tupleStore,
 									  TupleDesc tupleDescriptor);
 
 /*
@@ -62,18 +61,20 @@ static void ReturnReplicationSlotInfo(HTAB *shardInfoHashMap, Tuplestorestate *t
  * This meta information is stored in a shared memory segment and accessed
  * by logical decoding plugin.
  *
- * Split information is given by user as an Array of custom data type 'citus.split_shard_info'.
- * (worker_split_shard_replication_setup(citus.split_shard_info[]))
+ * Split information is given by user as an Array of custom data type 'pg_catalog.split_shard_info'.
+ * (worker_split_shard_replication_setup(pg_catalog.split_shard_info[]))
  *
- * Fields of custom data type 'citus.split_shard_info':
+ * Fields of custom data type 'pg_catalog.split_shard_info':
  * source_shard_id - id of the shard that is undergoing a split
  *
+ * distribution_column - Distribution column name
+ *
  * child_shard_id  - id of shard that stores a specific range of values
  *                   belonging to sourceShardId(parent)
  *
- * shard_min_value - lower bound(inclusive) of hash value which childShard stores.
+ * shard_min_value - Lower bound(inclusive) of hash value which childShard stores
  *
- * shard_max_value - upper bound(inclusive) of hash value which childShard stores
+ * shard_max_value - Upper bound(inclusive) of hash value which childShard stores
  *
  * node_id         - Node where the childShardId is located
  *
@@ -81,7 +82,7 @@ static void ReturnReplicationSlotInfo(HTAB *shardInfoHashMap, Tuplestorestate *t
  * <nodeId, tableOwner> pair. Multiple shards can be placed on the same destination node.
  * Source and destination nodes can be same too.
  *
- * There is a 1-1 mapping between a table owner and a replication slot. One replication
+ * There is a 1-1 mapping between a (table owner, node) and replication slot. One replication
  * slot takes care of replicating changes for all shards belonging to the same owner on a particular node.
  *
  * During the replication phase, WAL senders will attach to the shared memory
@@ -140,15 +141,14 @@ worker_split_shard_replication_setup(PG_FUNCTION_ARGS)
 	ShardSplitInfoSMHeader *splitShardInfoSMHeader =
 		CreateSharedMemoryForShardSplitInfo(shardSplitInfoCount, &dsmHandle);
 
-	PopulateShardSplitInfoInSM(splitShardInfoSMHeader,
-							   ShardInfoHashMap);
+	PopulateShardSplitInfoInSM(splitShardInfoSMHeader);
 
 	/* store handle in statically allocated shared memory*/
 	StoreShardSplitSharedMemoryHandle(dsmHandle);
 
 	TupleDesc tupleDescriptor = NULL;
 	Tuplestorestate *tupleStore = SetupTuplestore(fcinfo, &tupleDescriptor);
-	ReturnReplicationSlotInfo(ShardInfoHashMap, tupleStore, tupleDescriptor);
+	ReturnReplicationSlotInfo(tupleStore, tupleDescriptor);
 
 	PG_RETURN_VOID();
 }
@@ -184,7 +184,7 @@ SetupHashMapForShardInfo()
  *
  * sourceShardIdToSplit - Existing shardId which has a valid entry in cache and catalogue
  * partitionColumnName  - Name of column to use for partitioning
- * desSplitChildShardId - New split child shard which doesn't have an entry in metacache yet.
+ * desSplitChildShardId - New split child shard which doesn't have an entry in metacache yet
  * minValue				- Minimum hash value for desSplitChildShardId
  * maxValue				- Maximum hash value for desSplitChildShardId
  * nodeId				- NodeId where
@@ -291,16 +291,12 @@ AddShardSplitInfoEntryForNodeInMap(ShardSplitInfo *shardSplitInfo)
  * process during logical replication.
  *
  * shardSplitInfoSMHeader - Shared memory header
- *
- * shardInfoHashMap    - Hashmap containing parsed split information
- *                       per nodeId wise
  */
 static void
-PopulateShardSplitInfoInSM(ShardSplitInfoSMHeader *shardSplitInfoSMHeader,
-						   HTAB *shardInfoHashMap)
+PopulateShardSplitInfoInSM(ShardSplitInfoSMHeader *shardSplitInfoSMHeader)
 {
 	HASH_SEQ_STATUS status;
-	hash_seq_init(&status, shardInfoHashMap);
+	hash_seq_init(&status, ShardInfoHashMap);
 
 	NodeShardMappingEntry *entry = NULL;
 	int splitInfoIndex = 0;
@@ -360,6 +356,10 @@ NodeShardMappingHashCompare(const void *left, const void *right, Size keysize)
 }
 
 
+/*
+ * ParseShardSplitInfoFromDatum deserializes individual fields of 'pg_catalog.split_shard_info'
+ * datatype.
+ */
 static void
 ParseShardSplitInfoFromDatum(Datum shardSplitInfoDatum,
 							 uint64 *sourceShardId,
@@ -421,12 +421,18 @@ ParseShardSplitInfoFromDatum(Datum shardSplitInfoDatum,
 }
 
 
+/*
+ * ReturnReplicationSlotInfo writes 'pg_catalog.replication_slot_info'
+ * records to tuplestore.
+ * This information is used by the coordinator to create replication slots as a
+ * part of non-blocking split workflow.
+ */
 static void
-ReturnReplicationSlotInfo(HTAB *shardInfoHashMap, Tuplestorestate *tupleStore, TupleDesc
+ReturnReplicationSlotInfo(Tuplestorestate *tupleStore, TupleDesc
 						  tupleDescriptor)
 {
 	HASH_SEQ_STATUS status;
-	hash_seq_init(&status, shardInfoHashMap);
+	hash_seq_init(&status, ShardInfoHashMap);
 
 	NodeShardMappingEntry *entry = NULL;
 	while ((entry = (NodeShardMappingEntry *) hash_seq_search(&status)) != NULL)

src/backend/distributed/shardsplit/shardsplit_decoder.c

@@ -14,13 +14,6 @@
 #include "replication/logical.h"
 #include "utils/typcache.h"
 
-/*
- * Dynamically-loaded modules are required to include this macro call to check for
- * incompatibility (such as being compiled for a different major PostgreSQL version etc).
- * In a multiple source-file module, the macro call should only appear once.
- */
-PG_MODULE_MAGIC;
-
 extern void _PG_output_plugin_init(OutputPluginCallbacks *cb);
 static LogicalDecodeChangeCB pgoutputChangeCB;
 

src/backend/distributed/shardsplit/shardsplit_logical_replication.c

@@ -2,7 +2,7 @@
  *
  * shardsplit_logical_replication.c
  *
- * Function definitions for logically replicating split children.
+ * Function definitions for logically replicating shard to split children.
  *
  * Copyright (c) Citus Data, Inc.
  *
@@ -433,11 +433,7 @@ DropExistingIfAnyAndCreateTemplateReplicationSlot(ShardInterval *shardIntervalTo
 	PQclear(result);
 	ForgetResults(sourceConnection);
 
-	/*
-	 * Note: Temporary slot are only live during the session's lifetime causing them to be dropped when the session ends.
-	 */
 	StringInfo createReplicationSlotCommand = makeStringInfo();
-
 	appendStringInfo(createReplicationSlotCommand,
 					 "CREATE_REPLICATION_SLOT %s LOGICAL citus EXPORT_SNAPSHOT;",
 					 ShardSplitTemplateReplicationSlotName(
@@ -587,7 +583,7 @@ void
 DropAllShardSplitSubscriptions(MultiConnection *cleanupConnection)
 {
 	char *query = psprintf(
-		"SELECT subname FROM pg_subscription "
+		"SELECT subname FROM pg_catalog.pg_subscription "
 		"WHERE subname LIKE %s || '%%'",
 		quote_literal_cstr(SHARD_SPLIT_SUBSCRIPTION_PREFIX));
 	List *subscriptionNameList = GetQueryResultStringList(cleanupConnection, query);
@@ -608,7 +604,7 @@ static void
 DropAllShardSplitPublications(MultiConnection *connection)
 {
 	char *query = psprintf(
-		"SELECT pubname FROM pg_publication "
+		"SELECT pubname FROM pg_catalog.pg_publication "
 		"WHERE pubname LIKE %s || '%%'",
 		quote_literal_cstr(SHARD_SPLIT_PUBLICATION_PREFIX));
 	List *publicationNameList = GetQueryResultStringList(connection, query);
@@ -628,7 +624,7 @@ static void
 DropAllShardSplitUsers(MultiConnection *connection)
 {
 	char *query = psprintf(
-		"SELECT rolname FROM pg_roles "
+		"SELECT rolname FROM pg_catalog.pg_roles "
 		"WHERE rolname LIKE %s || '%%'",
 		quote_literal_cstr(SHARD_SPLIT_SUBSCRIPTION_ROLE_PREFIX));
 	List *usernameList = GetQueryResultStringList(connection, query);
@@ -649,7 +645,7 @@ static void
 DropAllShardSplitReplicationSlots(MultiConnection *cleanupConnection)
 {
 	char *query = psprintf(
-		"SELECT slot_name FROM pg_replication_slots "
+		"SELECT slot_name FROM pg_catalog.pg_replication_slots "
 		"WHERE slot_name LIKE %s || '%%'",
 		quote_literal_cstr(SHARD_SPLIT_REPLICATION_SLOT_PREFIX));
 	List *slotNameList = GetQueryResultStringList(cleanupConnection, query);

src/backend/distributed/shardsplit/shardsplit_shared_memory.c

@@ -25,9 +25,6 @@ const char *SharedMemoryNameForHandleManagement =
 
 static shmem_startup_hook_type prev_shmem_startup_hook = NULL;
 
-static
-void ShardSplitShmemInit(void);
-
 /* Function declarations */
 static ShardSplitInfoSMHeader * AllocateSharedMemoryForShardSplitInfo(int
 																	  shardSplitInfoCount,
@@ -35,9 +32,10 @@ static ShardSplitInfoSMHeader * AllocateSharedMemoryForShardSplitInfo(int
 																	  shardSplitInfoSize,
 																	  dsm_handle *
 																	  dsmHandle);
-
 static ShardSplitInfoSMHeader * GetShardSplitInfoSMHeaderFromDSMHandle(dsm_handle
 																	   dsmHandle);
+static dsm_handle GetShardSplitSharedMemoryHandle(void);
+static void ShardSplitShmemInit(void);
 
 /*
  * GetShardSplitInfoSMHeaderFromDSMHandle returns the header of the shared memory

src/backend/distributed/shared_library_init.c

@@ -106,6 +106,9 @@
 
 #include "columnar/columnar.h"
 
+/* marks shared object as one loadable by the postgres version compiled against */
+PG_MODULE_MAGIC;
+
 ColumnarSupportsIndexAM_type extern_ColumnarSupportsIndexAM = NULL;
 CompressionTypeStr_type extern_CompressionTypeStr = NULL;
 IsColumnarTableAmTable_type extern_IsColumnarTableAmTable = NULL;

src/include/distributed/shard_split.h

@@ -29,22 +29,6 @@ typedef enum SplitOperation
 	ISOLATE_TENANT_TO_NEW_SHARD
 } SplitOperation;
 
-/*
- * In-memory mapping of a split child shard.
- */
-typedef struct ShardSplitInfo
-{
-	Oid distributedTableOid;     /* citus distributed table Oid */
-	int partitionColumnIndex;    /* partition column index */
-	Oid sourceShardOid;          /* parent shard Oid */
-	Oid splitChildShardOid;      /* child shard Oid */
-	int32 shardMinValue;         /* min hash value */
-	int32 shardMaxValue;         /* max hash value */
-	uint32_t nodeId;             /* node where child shard is to be placed */
-	uint64 sourceShardId;        /* parent shardId */
-	uint64 splitChildShardId;        /* child shardId*/
-	char slotName[NAMEDATALEN];  /* replication slot name belonging to this node */
-} ShardSplitInfo;
 
 /*
  * SplitShard API to split a given shard (or shard group) using split mode and

src/include/distributed/shardsplit_logical_replication.h

@@ -2,7 +2,7 @@
  *
  * shardsplit_logical_replication.h
  *
- * Function declarations for logically replicating split children.
+ * Function declarations for logically replicating shard to split children.
  *
  * Copyright (c) Citus Data, Inc.
  *

src/include/distributed/shardsplit_shared_memory.h

@@ -14,7 +14,23 @@
 #ifndef SHARDSPLIT_SHARED_MEMORY_H
 #define SHARDSPLIT_SHARED_MEMORY_H
 
-#include "distributed/shard_split.h"
+/*
+ * In-memory mapping of a split child shard.
+ */
+typedef struct ShardSplitInfo
+{
+	Oid distributedTableOid;     /* citus distributed table Oid */
+	int partitionColumnIndex;    /* partition column index */
+	Oid sourceShardOid;          /* parent shard Oid */
+	Oid splitChildShardOid;      /* child shard Oid */
+	int32 shardMinValue;         /* min hash value */
+	int32 shardMaxValue;         /* max hash value */
+	uint32_t nodeId;             /* node where child shard is to be placed */
+	uint64 sourceShardId;        /* parent shardId */
+	uint64 splitChildShardId;        /* child shardId*/
+	char slotName[NAMEDATALEN];  /* replication slot name belonging to this node */
+} ShardSplitInfo;
+
 
 /*
  * Header of the shared memory segment where shard split information is stored.
@@ -52,7 +68,6 @@ typedef struct ShardSplitShmemData
 void InitializeShardSplitSMHandleManagement(void);
 
 void StoreShardSplitSharedMemoryHandle(dsm_handle dsmHandle);
-dsm_handle GetShardSplitSharedMemoryHandle(void);
 
 /* Functions for creating and accessing shared memory segments consisting shard split information */
 extern ShardSplitInfoSMHeader * CreateSharedMemoryForShardSplitInfo(int
@@ -65,5 +80,5 @@ extern ShardSplitInfoSMHeader *  GetShardSplitInfoSMHeader(void);
 extern HTAB * PopulateSourceToDestinationShardMapForSlot(char *slotName, MemoryContext
 														 cxt);
 
-char * encode_replication_slot(uint32_t nodeId, uint32_t tableOwnerId);
+extern char * encode_replication_slot(uint32_t nodeId, uint32_t tableOwnerId);
 #endif /* SHARDSPLIT_SHARED_MEMORY_H */