Hadoop Hbase query
Phoenix is a good solution for low latency result from Hbase tables than Hive.
It is good for range scans than Hbase scanners because they use secondary indexes and SkipScan.
As in your case , you use Python and phoenix API have only JDBC connectors.
Else Try Hbase Coprocessors. Which do SUM, MAX, COUNT,AVG functions.
you can enable coprocessors while creating table and can USE the Coprocessor functions
You can try Impala, which provide an ODBC connector, JDBC connector. Impala uses hive metatable for executing massively parallel batch execution.
You need to create a Hive metatable for your Hbase Table.
I have the below setup

2 node hadoop/hbase cluster with thirft server running on hbase.
Hbase has a table with 10 million rows.

I need to run aggregate queries like sum() on the hbase table
to show it on the web(charting purpose).
For now I am using python(thrift client) to get the dataset and display.
I am looking for database(hbase) level aggregation function to use in the web.
Any thoughts?