fix: refs #7126 Slow update

db/versions/11042-turquoiseAspidistra/00-firstScript.sql

@@ -1,8 +1,21 @@
 ALTER TABLE bs.waste ADD buyerFk int(10) unsigned NOT NULL;
 
+CREATE OR REPLACE TEMPORARY TABLE tBuyers
+	ENGINE = MEMORY
+	WITH tDistinctBuyers AS (
+		SELECT DISTINCT buyer
+			FROM bs.waste w
+	)
+	SELECT buyer, u.id
+		FROM tDistinctBuyers tdb
+			JOIN account.`user` u ON u.name = tdb.buyer COLLATE utf8mb3_unicode_ci
+
+
 UPDATE bs.waste w
-		JOIN account.`user` u ON u.name = w.buyer COLLATE utf8mb3_unicode_ci
-	SET w.buyerFk = u.id;
+		JOIN tBuyers tb ON tb.buyer = w.buyer
+	SET w.buyerFk = tb.id;
+
+DROP TEMPORARY TABLE tBuyers;
 
 ALTER TABLE bs.waste
     DROP PRIMARY KEY,