Improve Performance (#927)

* Stock-Overview: Reduce amount of database queries and FindObjectInArray()-calls

* Speed-up stock_current by improving products_resolved and creating indices.

* Review

Co-authored-by: Bernd Bestel <bernd@berrnd.de>

migrations/0106.sql

@@ -0,0 +1,29 @@
+CREATE INDEX ix_products_performance1 ON products (
+    parent_product_id
+);
+
+CREATE INDEX ix_products_performance2 ON products (
+    CASE WHEN parent_product_id IS NULL THEN id ELSE parent_product_id END,
+    active
+);
+
+CREATE INDEX ix_stock_performance1 ON stock (
+    product_id,
+    open,
+    best_before_date,
+    amount
+);
+
+DROP VIEW products_resolved;
+CREATE VIEW products_resolved
+AS
+SELECT
+    CASE
+        WHEN p.parent_product_id IS NULL THEN
+            p.id
+        ELSE
+            p.parent_product_id
+    END AS parent_product_id,
+    p.id as sub_product_id
+FROM products p
+WHERE p.active = 1;