-- TimescaleDB schema for MQTT telemetry ingestion.
-- Executed automatically on first container start.

CREATE EXTENSION IF NOT EXISTS timescaledb;

CREATE TABLE IF NOT EXISTS telemetry (
    time        TIMESTAMPTZ NOT NULL,
    topic       TEXT        NOT NULL,
    device_id   TEXT,
    payload     JSONB       NOT NULL
);

-- Convert to hypertable for time-series storage.
SELECT create_hypertable('telemetry', 'time', if_not_exists => TRUE);

-- Indexes for common query patterns.
-- (topic, time) and (device_id, time) serve the filtered API queries;
-- a bare (time) index serves the unfiltered /telemetry/latest lookup,
-- which would otherwise require a full backward scan of the hypertable.
CREATE INDEX IF NOT EXISTS idx_telemetry_topic_time ON telemetry (topic, time DESC);
CREATE INDEX IF NOT EXISTS idx_telemetry_device_time ON telemetry (device_id, time DESC);
CREATE INDEX IF NOT EXISTS idx_telemetry_time ON telemetry (time DESC);

-- Compression: older chunks are squeezed on a background schedule.
ALTER TABLE telemetry SET (
    timescaledb.compress,
    timescaledb.compress_segmentby = 'topic, device_id'
);

-- Compress chunks older than 7 days, drop data older than 1 year.
SELECT add_compression_policy('telemetry', INTERVAL '7 days');
SELECT add_retention_policy('telemetry', INTERVAL '365 days');