From 570ea064aa48c1a9f72aa98e021ecc80e71b24dd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Magnus=20=C3=85hall?= <magnus.ahall@gibon.se>
Date: Wed, 24 Jul 2024 15:39:04 +0200
Subject: [PATCH] Faster datapoint latest value display

---
 datapoint.go  | 37 ++++++++++++-------------------------
 sql/00026.sql |  6 ++++++
 2 files changed, 18 insertions(+), 25 deletions(-)

diff --git a/datapoint.go b/datapoint.go
index 2d2286e..e5687c2 100644
--- a/datapoint.go
+++ b/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)
diff --git a/sql/00026.sql b/sql/00026.sql
index 719dccd..364ccaa 100644
--- a/sql/00026.sql
+++ b/sql/00026.sql
@@ -1,4 +1,5 @@
 /* Adding last values to the datapoint table since they are a regularly used value. */
+ALTER TABLE public.datapoint ADD COLUMN last_value_id int4 NULL;
 ALTER TABLE public.datapoint ADD COLUMN last_value_int int8 NULL;
 ALTER TABLE public.datapoint ADD COLUMN last_value_string varchar NULL;
 ALTER TABLE public.datapoint ADD COLUMN last_value_datetime timestamptz NULL;
@@ -8,12 +9,14 @@ ALTER TABLE public.datapoint ADD COLUMN last_value_datetime timestamptz NULL;
 /* Once-run query to update it to the latest, to avoid user having to wait for the next entry. */
 UPDATE public.datapoint AS dp
 SET
+    last_value_id = dpv.id,
     last_value_int = dpv.value_int,
     last_value_string = dpv.value_string,
     last_value_datetime = dpv.value_datetime
 FROM (
 	SELECT
 		dp.id AS datapoint_id,
+		dpv.id,
 		dpv.value_int,
 		dpv.value_string,
 		dpv.value_datetime
@@ -39,6 +42,9 @@ $$
 BEGIN
 	UPDATE public.datapoint
 	SET
+		nodata_is_problem   = false,
+		last_value          = NEW.ts,
+		last_value_id       = NEW.id,
 		last_value_int      = NEW.value_int,
 		last_value_string   = NEW.value_string,
 		last_value_datetime = NEW.value_datetime