Awesome
lttb-sql
sample of PL/PGSQL to implement LTTB algorithm for down sampling
See: https://github.com/sveinn-steinarsson/flot-downsample
To test the function
CREATE TABLE sample_data (
id SERIAL PRIMARY KEY,
point_data POINT
);
\COPY sample_data FROM source.csv WITH CSV;
WITH selected_data AS (
SELECT array_agg(point_data) AS data_array
FROM sample_data
)
SELECT * FROM largest_triangle_three_buckets(
(SELECT data_array FROM selected_data),
500
);
Another example
-- query to downsample 3600 points of sine wave to 10 points
WITH selected_data AS (
SELECT array_agg(POINT(x, sin(radians(x)))) AS data_array
FROM generate_series(-180, 180, 0.1) AS x
)
SELECT * FROM largest_triangle_three_buckets(
(SELECT data_array FROM selected_data),
10
);