even more precise load calculation

thanks Zegarek <https://stackoverflow.com/users/5298879>

acquire/schema.sql

@@ -92,36 +92,35 @@ BEGIN
 			SELECT ts, len FROM p
 			WHERE NOT p.isdrop
 		    ),
-		    counted AS (
-			SELECT ts, len AS pktsizebytes,
-			    sum(len) OVER (
-				ORDER BY ts
-				-- 0.1 PRECEDING ⇒ 100ms sliding window
-				RANGE BETWEEN 0.1 PRECEDING AND CURRENT ROW EXCLUDE CURRENT ROW
-			    ) AS lensum, min(ts) OVER (
-				ORDER BY ts
-				-- same sliding window as above!
-				RANGE BETWEEN 0.1 PRECEDING AND CURRENT ROW EXCLUDE CURRENT ROW
-			    ) AS tsmin
-			FROM prefiltered
-		    ),
-		    merged AS (
-			SELECT ts, pktsizebytes, lensum, tsmin, bwlim,
+		    calculated AS (
+			SELECT ts, len AS pktsizebytes, bwlim,
 			    -- https://dba.stackexchange.com/a/105828/65843
-			    count(bwlim) OVER (ORDER BY ts) AS ct
-			FROM counted FULL OUTER JOIN q USING (ts)
+			    count(bwlim) OVER wts AS ct,
+			    -- https://stackoverflow.com/a/77051480/2171120
+			    CASE WHEN (COUNT(*) OVER wtim) > 20
+			    THEN 8 * (sum(len) OVER wnum) / NULLIF(ts - min(ts) OVER wnum, 0)
+			    ELSE 8 * (sum(len) OVER wtim) / NULLIF(ts - min(ts) OVER wtim, 0)
+			    END AS bps
+			FROM prefiltered FULL OUTER JOIN q USING (ts)
+			WINDOW
+			    wnum AS (ORDER BY ts
+				ROWS BETWEEN 20 PRECEDING AND CURRENT ROW
+				EXCLUDE CURRENT ROW),
+			    wtim AS (ORDER BY ts
+				RANGE BETWEEN 0.1 PRECEDING AND CURRENT ROW
+				EXCLUDE CURRENT ROW),
+			    wts AS (ORDER BY ts)
 		    ),
-		    divided AS (
-			SELECT ts, pktsizebytes,
-			    8 * lensum / NULLIF(ts - tsmin, 0) AS bps,
+		    filled AS (
+			SELECT ts, pktsizebytes, bps,
 			    min(bwlim) OVER (PARTITION BY ct) AS bw
-			FROM merged
+			FROM calculated
 		    )
 		SELECT ts - d AS dts,
 		    (bps::NUMERIC(10,0) / 1000000)::NUMERIC(10,6) AS load,
 		    (bw::NUMERIC(10,0) / 1000000)::NUMERIC(10,6) AS capacity,
 		    pktsizebytes
-		FROM divided, o ORDER BY ts;
+		FROM filled, o ORDER BY ts;
 	RETURN sid;
 END;
 $$ LANGUAGE 'plpgsql';