integral()

Calculate the integral from a TimeWeightSummary

Since 1.15.0

Calculate the integral, or the area under the curve formed by the data points. Equal to average multiplied by the elapsed time.

Samples

Create a table to track irregularly sampled storage usage in bytes, and get the total storage used in byte-hours. Use the ‘last observation carried forward’ interpolation method:

-- Create a table to track irregularly sampled storage usage
CREATE TABLE user_storage_usage(ts TIMESTAMP, storage_bytes BIGINT);
INSERT INTO user_storage_usage(ts, storage_bytes) VALUES
    ('01-01-2022 00:00', 0),
    ('01-01-2022 00:30', 100),
    ('01-01-2022 03:00', 300),
    ('01-01-2022 03:10', 1000),
    ('01-01-2022 03:25', 817);

-- Get the total byte-hours used
SELECT
    integral(time_weight('LOCF', ts, storage_bytes), 'hours')
FROM
    user_storage_usage;

Arguments

The syntax is:

integral(
    tws TimeWeightSummary
    [, unit TEXT]
) RETURNS DOUBLE PRECISION

Name	Type	Default	Required	Description
tws	TimeWeightSummary	-	✔	The input TimeWeightSummary from a time_weight() call
unit	TEXT	second		The unit of time to express the integral in. Can be microsecond, millisecond, second, minute, hour, or any alias for those units supported by Postgres

Returns

Column	Type	Description
integral	DOUBLE PRECISION	The time-weighted integral.