Add guc variable for shard count

src/backend/distributed/master/master_node_protocol.c

@@ -55,6 +55,7 @@
 
 
 /* Shard related configuration */
+int ShardCount = 32;
 int ShardReplicationFactor = 2; /* desired replication factor for shards */
 int ShardMaxSize = 1048576;     /* maximum size in KB one shard can grow to */
 int ShardPlacementPolicy = SHARD_PLACEMENT_ROUND_ROBIN;

src/backend/distributed/shared_library_init.c

@@ -332,6 +332,17 @@ RegisterCitusConfigVariables(void)
 		0,
 		NULL, NULL, NULL);
 
+	DefineCustomIntVariable(
+		"citus.shard_count",
+		gettext_noop("Sets the number of shards for a new hash-partitioned table"
+					 "created with create_distributed_table()."),
+		NULL,
+		&ShardCount,
+		32, 1, 64000,
+		PGC_USERSET,
+		0,
+		NULL, NULL, NULL);
+
 	DefineCustomIntVariable(
 		"citus.shard_replication_factor",
 		gettext_noop("Sets the replication factor for shards."),

src/include/distributed/master_protocol.h

@@ -82,6 +82,7 @@ typedef enum
 
 
 /* Config variables managed via guc.c */
+extern int ShardCount;
 extern int ShardReplicationFactor;
 extern int ShardMaxSize;
 extern int ShardPlacementPolicy;