intercept()

The intercept of the least squares fit line computed from the adjusted counter values and times input in the CounterSummary. This corresponds to the projected value at the PostgreSQL epoch (2000-01-01 00:00:00+00). This is useful for drawing the best fit line on a graph, using the slope and the intercept.

intercept(
    summary CounterSummary
) RETURNS DOUBLE PRECISION

For more information about counter aggregation functions, see the hyperfunctions documentation.

SELECT
    id,
    bucket,
    intercept(summary)
FROM (
    SELECT
        id,
        time_bucket('15 min'::interval, ts) AS bucket,
        counter_agg(ts, val) AS summary
    FROM foo
    GROUP BY id, time_bucket('15 min'::interval, ts)
) t