counter_agg()

An aggregate that produces a CounterSummary from timestamps and associated values.

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

Required arguments

The value argument is currently only accepted as a DOUBLE PRECISION number, because it is the most common type for counters, even though other numeric types, such as BIGINT, might sometimes be more intuitive. If you store a value as a different numeric type you can cast to DOUBLE PRECISION on input to the function.

note

If there are NULL values in your data, the aggregate ignores them and aggregates only non-NULL values. If you only have NULL values, the aggregate returns NULL.

Optional arguments

The bounds argument represents the largest and smallest possible times that could be input to this aggregate. Calling with NULL, or leaving out the argument, results in an unbounded CounterSummary. Bounds are required for extrapolation, but not for other accessor functions.

Returns

Sample usage

This example produces a CounterSummary from timestamps and associated values, then computes the irate_right accessor:

2. WITH t as (

4. SELECT

6. time_bucket('1 day'::interval, ts) as dt,

8. counter_agg(ts, val) AS cs -- get a CounterSummary

10. FROM foo

12. WHERE id = 'bar'

14. GROUP BY time_bucket('1 day'::interval, ts)

16. )

18. SELECT

20. dt,

22. irate_right(cs) -- extract instantaneous rate from the CounterSummary

24. FROM t;