lttb()
Toolkit
TimescaleDB Toolkit functions are available under Timescale Community Edition. They are automatically included with Timescale Cloud. Click to learn more.

Largest Triangle Three Buckets is a downsampling method that tries to retain visual similarity between the downsampled data and the original dataset. The TimescaleDB Toolkit implementation of this takes (timestamp, value) pairs, sorts them if needed, and downsamples them.

Required arguments

Name	Type	Description
`time`	`TIMESTAMPTZ`	Time (x) value for the data point
`value`	`DOUBLE PRECISION`	Data (y) value for the data point
`resolution`	`INTEGER`	Number of points the output should have

Returns

Column	Type	Description
`timevector`	`Timevector`	A `timevector` object containing the downsampled points. It can be unpacked with `unnest`.

Sample usage

This examples uses a table with raw data generated as a sine wave:


SET TIME ZONE 'UTC';
CREATE TABLE metrics(date TIMESTAMPTZ, reading DOUBLE PRECISION);
INSERT INTO metrics
SELECT
    '2020-1-1 UTC'::timestamptz + make_interval(hours=>foo),
    (5 + 5 * sin(foo / 24.0 * PI()))
    FROM generate_series(1,168) foo;

You can use LTTB to dramatically reduce the number of points while still capturing the peaks and valleys in the data:


SELECT time, value
FROM unnest((
    SELECT lttb(date, reading, 8)
    FROM metrics))

The output looks like this:


time          |        value        
------------------------+---------------------
 2020-01-01 01:00:00+00 |   5.652630961100257
 2020-01-01 13:00:00+00 |   9.957224306869053
 2020-01-02 11:00:00+00 | 0.04277569313094798
 2020-01-03 11:00:00+00 |   9.957224306869051
 2020-01-04 13:00:00+00 | 0.04277569313094709
 2020-01-05 16:00:00+00 |   9.330127018922191
 2020-01-06 20:00:00+00 |  2.4999999999999996
 2020-01-08 00:00:00+00 |   5.000000000000004

lttb() ToolkitTimescaleDB Toolkit functions are available under Timescale Community Edition. They are automatically included with Timescale Cloud. Click to learn more.

Required arguments

Returns

Sample usage

Related Content

lttb()
Toolkit
TimescaleDB Toolkit functions are available under Timescale Community Edition. They are automatically included with Timescale Cloud. Click to learn more.