A few fixes

Author: davidjahn

skills/mongodb-query-optimizer/references/core-indexing-principles.md

@@ -8,7 +8,7 @@ The first field of the index should be in the query's filter or sort condition.
 
 - **Equality** fields first (e.g. `{field: value}`, `{$in: [...]}` with \<= 200 elements, `{field: {$eq: value}}`)
 - **Sort** fields next  
-- **Range** fields last (e.g. `$gt`, `$lt`, `$gte`, `$lte`, `{$in: [...]}` with \> 200 elements in the array), `$ne, anchored case-sensitive $regex`)
+- **Range** fields last (e.g. `$gt`, `$lt`, `$gte`, `$lte`, `{$in: [...]}` with \> 200 elements in the array, `$ne`, anchored case-sensitive `$regex`)
 
 If equality is not very selective and range is, then ERS may perform better than ESR.
 

testing/mongodb-query-optimizer/evals/evals.json

@@ -4,12 +4,12 @@
     {
       "id": 1,
       "prompt": "How do I optimize this query? db.orders.find({ status: 'open', tags: { $in: ['urgent', 'priority', 'escalated'] } }).sort({ createdAt: -1 }).limit(50). The tags field usually has 3-5 values per document but the $in list could grow to much larger from a user filter.",
-      "expected_output": "Recommends index { status: 1, tags: 1, createdAt: -1 }, notes that $in with many elements is treated as a range scan rather than equality.",
+      "expected_output": "Recommends index { status: 1, tags: 1, createdAt: 1 }, notes that $in with many elements is treated as a range scan rather than equality.",
       "files": [],
       "expectations": [
         "Recommends a compound index covering status, tags, and createdAt",
         "Mentions ESR ordering or explains equality-before-sort-before-range",
-        "Suggests that if the $in list stays small, { status: 1, tags: 1, createdAt: -1 } works, but if it grows large the performance is likely to degrade"
+        "Suggests that if the $in list stays small, { status: 1, tags: 1, createdAt: 1 } works, but if it grows large the performance is likely to degrade"
       ]
     },
     {

testing/mongodb-query-optimizer/setup-slow-queries.ts

@@ -189,12 +189,15 @@ async function main() {
     console.log(`  Inserted ${customers.length} customers`);
 
     console.log(`Generating ${NUM_ORDERS} orders...`);
-    const orders = generateOrders(customers, NUM_ORDERS);
-    // Insert in batches of 2000
-    for (let i = 0; i < orders.length; i += 2000) {
-      await db.collection("orders").insertMany(orders.slice(i, i + 2000));
+    const ORDERS_BATCH_SIZE = 2000;
+    let insertedOrders = 0;
+    for (let i = 0; i < NUM_ORDERS; i += ORDERS_BATCH_SIZE) {
+      const batchSize = Math.min(ORDERS_BATCH_SIZE, NUM_ORDERS - i);
+      const ordersBatch = generateOrders(customers, batchSize);
+      await db.collection("orders").insertMany(ordersBatch);
+      insertedOrders += ordersBatch.length;
     }
-    console.log(`  Inserted ${orders.length} orders`);
+    console.log(`  Inserted ${insertedOrders} orders`);
 
     // ------------------------------------------------------------------
     // 3. Run slow queries for ~30 seconds