ddsketch

pig build pkg ddsketch;		# build rpm/deb

pig repo add pgsql -u   # add both repo and update cache

pig install ddsketch;		# install via package name, for the active PG version

pig install ddsketch -v 18;   # install for PG 18
pig install ddsketch -v 17;   # install for PG 17
pig install ddsketch -v 16;   # install for PG 16
pig install ddsketch -v 15;   # install for PG 15
pig install ddsketch -v 14;   # install for PG 14

CREATE EXTENSION ddsketch;

CREATE EXTENSION ddsketch;

-- Instead of: SELECT percentile_cont(0.95) WITHIN GROUP (ORDER BY a) FROM t;
SELECT ddsketch_percentile(a, 0.05, 1024, 0.95) FROM t;

-- Multiple percentiles at once
SELECT ddsketch_percentile(a, 0.05, 1024, ARRAY[0.5, 0.95, 0.99]) FROM t;

-- Pre-aggregate for fast repeated queries
CREATE TABLE p AS SELECT a, b, ddsketch(c, 0.05, 1024) AS d FROM t GROUP BY a, b;

-- Query pre-aggregated data (~1.5ms vs ~7s for exact)
SELECT a, ddsketch_percentile(d, 0.95) FROM p GROUP BY a ORDER BY a;