⚡ Bolt: Fix N+1 query bottleneck in user orders

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2024-05-06 - Fixing N+1 Queries in User Orders
+**Learning:** In Drizzle ORM, querying related items within a loop (e.g., fetching order items for each order inside `Promise.all(orders.map(...))`) creates a classic N+1 query bottleneck. This codebase's serverless Neon PostgreSQL setup makes query round-trip times especially punitive.
+**Action:** Always batch related fetches. Use `inArray` to query all related items in a single shot (e.g., `where(inArray(orderItems.orderId, orderIds))`) and then map them in memory using a hash map or `Map` structure for O(1) assignment.

lib/actions/orders.ts

@@ -3,7 +3,7 @@
 import { db } from "@/lib/db";
 import { orders, orderItems, products, productVariants, user, bargainSessions } from "@/lib/db/schema";
 import { getServerSession } from "@/lib/auth-server";
-import { eq, desc, sql, and, isNull } from "drizzle-orm";
+import { eq, desc, sql, and, isNull, inArray } from "drizzle-orm";
 import { revalidatePath } from "next/cache";
 import { markCouponUsed } from "./admin";
 
@@ -297,20 +297,31 @@ export async function getUserOrders() {
     .where(eq(orders.userId, session.user.id))
     .orderBy(desc(orders.createdAt));
 
-  // Fetch items for each order
-  const ordersWithItems = await Promise.all(
-    userOrders.map(async (order) => {
-      const items = await db
-        .select()
-        .from(orderItems)
-        .where(eq(orderItems.orderId, order.id));
+  if (userOrders.length === 0) {
+    return [];
+  }
 
-      return {
-        ...order,
-        items,
-      };
-    })
-  );
+  // ⚡ Bolt Performance Optimization: Fix N+1 Query
+  // Fetch all order items in a single query instead of one query per order
+  const orderIds = userOrders.map(order => order.id);
+  const allItems = await db
+    .select()
+    .from(orderItems)
+    .where(inArray(orderItems.orderId, orderIds));
+
+  // Group items by order ID for O(1) lookup
+  const itemsByOrderId = new Map<string, typeof allItems>();
+  for (const item of allItems) {
+    if (!itemsByOrderId.has(item.orderId)) {
+      itemsByOrderId.set(item.orderId, []);
+    }
+    itemsByOrderId.get(item.orderId)!.push(item);
+  }
+
+  const ordersWithItems = userOrders.map(order => ({
+    ...order,
+    items: itemsByOrderId.get(order.id) || [],
+  }));
 
   return ordersWithItems;
 }