**pg_hdr_histogram** is a PostgreSQL extension for exact-latency percentiles.
Most monitoring tools approximate percentiles from fixed buckets. pg_hdr_histogram stores a full HDR histogram as a first-class type, so `p50` / `p99` / `p99.9` are measurements (~0.1% relative precision over 6 orders of magnitude), not estimates — and histograms merge losslessly across time windows and hosts. - Built on HdrHistogram_c. - Aggregates `hdr_add` and `hdr_merge`, parallel-safe, `trusted = true`. - Author: Vladimir Pavliv. Source: [https://github.com/vovcke/pg_hdr_histogram](https://github.com/vovcke/pg_hdr_histogram)
