feat(stats): add bounded path and hash-width analytics (#159)

db/queries/paths.sql

@@ -0,0 +1,21 @@
+-- name: GetPathStats :many
+-- All HTTP aggregates read the compact classification snapshot.
+WITH readings AS (
+    SELECT * FROM mv_path_stats_hourly
+    WHERE hour >= @since::timestamptz AND hour < @until::timestamptz
+      AND COALESCE(cardinality(@iatas::bpchar[]), 0) = 0
+    UNION ALL
+    SELECT * FROM mv_path_stats_hourly
+    WHERE hour >= @since::timestamptz AND hour < @until::timestamptz
+      AND cardinality(@iatas::bpchar[]) > 0 AND iata = ANY(@iatas::bpchar[])
+)
+SELECT (grouping(hour) = 0)::boolean AS is_hourly,
+       COALESCE(hour, 'epoch'::timestamptz)::timestamptz AS hour,
+       category, hash_bytes, COALESCE(entries, 0)::integer AS entries,
+       sum(receptions)::bigint AS receptions
+FROM readings
+GROUP BY GROUPING SETS ((category, hash_bytes, entries), (hour, category, hash_bytes))
+ORDER BY is_hourly, hour, category, hash_bytes, entries;
+
+-- name: RefreshPathStats :exec
+REFRESH MATERIALIZED VIEW CONCURRENTLY mv_path_stats_hourly;