table_collocation_api.py

```
CREATE TABLE pg_dist_colocation 
	(shardCount INT, workerNodeList [TEXT], replicationFactor INT, colocationId SERIAL, 
	UNIQUE (shardCount, workerNodeList))
```
ALTER TABLE pg_dist_partition ADD COLUMN colocationId INT;


def create_hash_partitioned_table(tableName, partitionColumn):

	shardCount = citus.shardCount
	workerNodeList = WorkerNodeList()

	colocationId = GetOrInsertColocationId(shardCount, workerNodeList, replicationFactor
		)

	CreateDistributedTable('tableName'::regclass, DISTRIBUTED_BY_HASH, partitionColumn, colocationId);
	CreateWorkerShards('tableName'::regclass, shardCount, replicationFactor);




def GetOrInsertColocationId(shardCountIn, workerNodeListIn, replicationFactorIn):

```
INSERT INTO	
	pg_dist_colocation (shardCount, workerNodeList, replicationFactor) VALUES
					   (shardCountIn, workerNodeListIn, replicationFactorIn)
	ON CONFLICT (shardCount, workerNodeList) DO NOTHING
	RETURNING colocationId;	
```

def rebalance_colocated_tables(tableName):

	colocationId = ColocationId(tableName)

	AcquireExlusiveLock(colocationId)

	colocatedTableList = ColocatedTableList(colocationId)
	for colocatedTable in colocatedTableList:

		sortedShardPlacementList = SortShardPlacementList()




def SortShardPlacementList(relationId):

	shardPlacementList = ShardPlcementList(relationId)

	# sort the placements wrt shardId, nodeHost, and nodePort
	sortedShardPlacementList = SortList (shardPlacementList, [shardId, nodeHost, nodePort])

	return sortedShardPlacementList