Store/Retrieve time series data from PostgreSQL

Hi

*Requirement :- *
We need to retrieve latest health of around 1.5 million objects for a given
time.

*Implementation :-*
We are storing hourly data of each object in single row. Given below is the
schema :-

*CREATE TABLE health_timeseries (*

* mobid text NOT NULL,
hour bigint NOT NULL,
health real[]
);*

mobId - Object ID

hour - Epoch hour

health - Array of health values for a given hour of that object.

Each object has 2 hours of health data (i.e. 2 rows for each object)
so total no. of rows is around 3 million.

With the above approach the query to retrieve the latest health of all
objects for a given time duration is taking around *85 seconds*. I
have tried to increase the work_mem, effective_cache, shared_buffer to
4 GB of PostgreSQL but still there was no improvement in the query
execution time.

*Query :-*

*select distinct on (health_timeseries.mobid) mobid,
health_timeseries.health, health_timeseries.hour from
health_timeseries where hour >=(1505211054000/(3600*1000))-1 and hour
<= 1505211054000/(3600*1000) ORDER BY health_timeseries.mobid DESC,
health_timeseries.hour DESC;*

*Hardware Configuration of PostgreSQL VM :-*

1. OS - Centos.

2. Postgresql version - 9.6.2

3. RAM - 16 GB RAM

4. CPU - 8 vCPU

Please let us know the hardware configuration of PostgreSQL for such
huge dataset?

And also let us know if there is any better schema/query to retrieve this data?

Thanks and Regards

Subramaniam