slope()

The slope of the least squares fit line computed from the adjusted counter values and times input in the CounterSummary. Because the times are input as seconds, the slope provides a per-second rate of change estimate based on the least squares fit, which is often similar to the result of the rate calculation, but can more accurately reflect the usual behavior if there are infrequent, large changes in a counter.

2. slope(

4. summary CounterSummary

6. ) RETURNS DOUBLE PRECISION

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

Required arguments

Name Type Description
summary CounterSummary The input CounterSummary from a counter_agg call

Returns

Name Type Description
slope DOUBLE PRECISION The per second rate of change computed by taking the slope of the least squares fit of the points input in the CounterSummary

Sample usage

2. SELECT

4. id,

6. bucket,

8. slope(summary)

10. FROM (

12. SELECT

14. id,

16. time_bucket('15 min'::interval, ts) AS bucket,

18. counter_agg(ts, val) AS summary

20. FROM foo

22. GROUP BY id, time_bucket('15 min'::interval, ts)

24. ) t