Faster datapoint latest value display

datapoint.go

@@ -162,8 +162,6 @@ func DatapointAdd[T any](name string, value T) (err error) { // {{{
 		return
 	}
 
-	service.Db.Conn.Exec(`UPDATE datapoint SET last_value = NOW(), nodata_is_problem = false WHERE id=$1`, dpID)
-
 	return
 } // }}}
 
@@ -172,30 +170,19 @@ func DatapointsRetrieve() (dps []Datapoint, err error) { // {{{
 	var rows *sqlx.Rows
 	rows, err = service.Db.Conn.Queryx(`
 		SELECT
-			dp.id,
-			dp.name,
-			dp.datatype,
-			dp.last_value,
-			dp.group,
-			dp.comment,
-			dp.nodata_problem_seconds,
-
-			dpv.id AS v_id,
-			dpv.ts,
-			dpv.value_int,
-			dpv.value_string,
-			dpv.value_datetime
-
-		FROM public.datapoint dp
-		LEFT JOIN (
-			SELECT
-				*, 
-				row_number() OVER (PARTITION BY "datapoint_id" ORDER BY ts DESC) AS rn
-			FROM datapoint_value
-		) dpv ON dpv.datapoint_id = dp.id AND rn = 1
+			id, name, datatype, last_value, "group", comment, nodata_problem_seconds,
+			last_value_id AS v_id,
+			CASE
+				WHEN last_value_id IS NULL THEN null
+				ELSE last_value
+			END AS ts,
+			last_value_int AS value_int,
+			last_value_string AS value_string,
+			last_value_datetime AS value_datetime
+		FROM datapoint
 		ORDER BY
-			dp.group ASC,
-			dp.name ASC
+			"group" ASC,
+			name ASC
 	`)
 	if err != nil {
 		err = werr.Wrap(err)