feat(stats): report the longest path per hour in /stats/paths

db/sqlc/paths.sql.go

@@ -24,7 +24,9 @@ WITH readings AS (
 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
+       sum(receptions)::bigint AS receptions,
+       -- Non-routed categories store entries = 0, so an hour of only empty paths gives 0.
+       COALESCE(max(entries) FILTER (WHERE receptions > 0), 0)::integer AS max_entries
 FROM readings
 GROUP BY GROUPING SETS ((category, hash_bytes, entries), (hour, category, hash_bytes))
 ORDER BY is_hourly, hour, category, hash_bytes, entries
@@ -43,6 +45,7 @@ type GetPathStatsRow struct {
 	HashBytes  int32              `json:"hash_bytes"`
 	Entries    int32              `json:"entries"`
 	Receptions int64              `json:"receptions"`
+	MaxEntries int32              `json:"max_entries"`
 }
 
 // All HTTP aggregates read the hourly rollup, never observations.
@@ -62,6 +65,7 @@ func (q *Queries) GetPathStats(ctx context.Context, arg GetPathStatsParams) ([]G
 			&i.HashBytes,
 			&i.Entries,
 			&i.Receptions,
+			&i.MaxEntries,
 		); err != nil {
 			return nil, err
 		}