num_changes()

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

    NameTypeDescription
    num_changesBIGINTThe number of times the value changed
    2. SELECT
    4.     id,
    7.     num_changes(summary)
    9. FROM (
    11.     SELECT
    13.         id,
    14.         time_bucket('15 min'::interval, ts) AS bucket,
    16.         counter_agg(ts, val) AS summary
    18.     FROM foo
    20.     GROUP BY id, time_bucket('15 min'::interval, ts)