Update 3. Get Only What You Need, and Fast.md

Author: ortizfram

Introduction to MongoDB in Python/3. Get Only What You Need, and Fast.md

@@ -247,3 +247,17 @@ five_most_common = Counter(n_born_and_affiliated).most_common(5)
 print(five_most_common)
 ```
      [('USA', 241), ('United Kingdom', 56), ('France', 26), ('Germany', 19), ('Japan', 17)]
+
+## 🦍 Setting a new limit?
+> How many documents does the following expression return?
+
+    list(db.prizes.find({"category": "economics"},
+                        {"year": 1, "_id": 0})
+         .sort("year")
+         .limit(3)
+         .limit(5))
+Possible Answers
+- [ ] 3: the first call to limit takes precedence
+- [x] 5: the second call to limit overrides the first
+- [ ] none: instead, an error is raised
+> reason : You can think of the query parameters as being updated like a dictionary in Python: `d = {'limit': 3}; d.update({'limit': 5}); print(d) will print "{'limit': 5}"`