Create index on (entity_id, time)

[sithmein]

Currently the TimescaleDB extension creates two indexes, on on entity_id and one on time. However, most queries will filter by both entity and time and therefore a compound index on both (entity_id, time DESC) will improve those queries considerably. The TimescaleDB manual also suggests creating such indexes.

[sithmein]

I realized, this is the wrong project. Submitted it again as Expaso/hassos-addon-timescaledb#6.