first_val, last_val

first_val, last_val

This pair of functions returns the values of the first and last points in a CounterSummary aggregate.

2. first_val(

4. cs CounterSummary

6. ) RETURNS DOUBLE PRECISION

8. last_val(

10. cs CounterSummary

12. ) RETURNS DOUBLE PRECISION

Required arguments

Name	Type	Description
`cs`	CounterSummary	The input CounterSummary from a previous `counter_agg` (point form) call, often from a continuous aggregate

Returns

Column	Type	Description
`first_val`	`DOUBLE PRECISION`	The value of the first point in the `CounterSummary`

Column	Type	Description
`last_val`	`DOUBLE PRECISION`	The value of the last point in the `CounterSummary`

Sample usage

This example produces a CounterSummary from timestamps and associated values, then applies the first_val and last_val accessors:

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 table

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

14. )

16. SELECT

18. dt,

20. first_val(cs) -- extract the value of the first point in the CounterSummary

22. last_val(cs) -- extract the value of the last point in the CounterSummary

24. FROM t;