Improve and debug calculate metrics script

inventory-server/db/migrations/add_metrics_indexes.sql

@@ -0,0 +1,17 @@
+-- Indexes for orders table
+CREATE INDEX IF NOT EXISTS idx_orders_product_date ON orders(product_id, date);
+CREATE INDEX IF NOT EXISTS idx_orders_date ON orders(date);
+
+-- Indexes for purchase_orders table
+CREATE INDEX IF NOT EXISTS idx_po_product_date ON purchase_orders(product_id, date);
+CREATE INDEX IF NOT EXISTS idx_po_product_status ON purchase_orders(product_id, status);
+CREATE INDEX IF NOT EXISTS idx_po_vendor ON purchase_orders(vendor);
+
+-- Indexes for product_metrics table
+CREATE INDEX IF NOT EXISTS idx_metrics_revenue ON product_metrics(total_revenue);
+
+-- Indexes for stock_thresholds table
+CREATE INDEX IF NOT EXISTS idx_thresholds_category_vendor ON stock_thresholds(category_id, vendor);
+
+-- Indexes for product_categories table
+CREATE INDEX IF NOT EXISTS idx_product_categories_both ON product_categories(product_id, category_id);