Postgres/TimescaleDB

• Postgres

Setup

CREATE TABLE sensor_data (
        time TIMESTAMPTZ NOT NULL,
        topic TEXT,
        value DOUBLE PRECISION
);

SELECT create_hypertable('sensor_data', 'time');

Insert data via Node-RED

INSERT INTO sensor_data (time, topic, value) VALUES (
    now(),
    '{{{ msg.topic }}}',
    '{{{ msg.payload }}}'
);

Get table size

SELECT hypertable_size('sensor_data');

Time bucket

• https://docs.timescale.com/use-timescale/latest/time-buckets/about-time-buckets/
• 15min average time_buckets

SELECT time_bucket('15 minute', time) as fifteen_min,
  avg(value) AS avg_value
FROM "sensor_data"
WHERE "topic" = 'home/plug-c86044-fridge/sensor/power'
GROUP by fifteen_min
ORDER by fifteen_min DESC
LIMIT 50

Counters

• https://github.com/timescale/timescaledb-toolkit/blob/main/docs/counter_agg.md
• https://stackoverflow.com/questions/76774353/get-complete-hours-time-buckets-with-timescaledb :

SELECT time_bucket('1 hour', time) as bucket,
 first(time,time) as period_begin,
 last(time,time) as period_end,
 MAX(counter) - MIN(counter) as total_consumption
FROM 
GROUP BY 1;

Links

• https://docs.timescale.com/
• https://www.timescale.com/learn/time-series-basics
• https://www.timescale.com/learn/timescale-basics