Store/Retrieve time series data from PostgreSQL

[Subramaniam C <subramaniam31784@xxxxxxxxx>]

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