Blog - Page 31

Homework: Homework 6.5 In this homework, you will build a small replica set on your own computer. We will check that it works with validate.js, which you should download from the Download Handout link. Create three directories for the three mongod processes. On UNIX or mac, this could be done as follows: mkdir -p /data/rs1 [...]

Homework: Homework 6.4 You have a sharded system with three shards and have sharded the collections "students" in the "school" database across those shards. The output of sh.status() when connected to Mongos looks like this: mongos> sh.status() — Sharding Status — sharding version: { "_id" : 1, "minCompatibleVersion" : 5, "currentVersion" : 6, "clusterId" : [...]

Homework: Homework 6.3 Which of the following statements are true about choosing and using a shard key? MongoDB can not enforce unique indexes on a sharded collection other than the shard key itself, or indexes prefixed by the shard key. There must be an index on the collection that starts with the shard key. You [...]

Homework: Homework 6.2 Let's suppose you have a five-member replica set and want to assure that writes are committed to the journal and are acknowledged by at least 3 nodes before you proceed forward. What would be the appropriate settings for w and j? Solution: w="majority"

Homework: Homework 6.1 Which of the following statements are true about replication in MongoDB? Check all that apply.

The solution to Homework 5.4 M101JS: MongoDB for Node.js Developers Homework: Homework 5.4 Removing Rural Residents In this problem, you will calculate the number of people who live in a zip code in the US where the city starts with a digit. We will take that to mean they don't really live in a city. Once [...]

The solution to Homework 5.3 (Hands-On) M101JS: MongoDB for Node.js DevelopersWho's the easiest grader on campus?A set of grades are loaded into the grades collection. The documents look like this: { "_id" : ObjectId("50b59cd75bed76f46522c392"), "student_id" : 10, "class_id" : 5, "scores" : [ { "type" : "exam", "score" : 69.17634380939022 }, { "type" : "quiz", [...]

The solution to Homework 5.2 (Hands-On) M101JS: MongoDB for Node.js Developers Crunching the Zipcode datasetPlease calculate the average population of cities in California (abbreviation CA) and New York (NY) (taken together) with populations over 25,000. For this problem, assume that a city name that appears in more than one state represents two separate cities. Please [...]

Homework: Homework 5.1 (Hands-On) Finding the most frequent author of comments on your blog In this assignment, you will use the aggregation framework to find the most frequent author of comments on your blog. We will be using the same basic dataset as last week, with posts and comments shortened considerably, and with many fewer [...]

HOMEWORK: HOMEWORK 4.3 Solution to HOMEWORK 4.3 M101JS: MongoDB for Node.js Developers NOTE there is a bug (TOOLS-939) affecting some versions of mongoimport and mongorestore that causes mongoimport -d blog -c posts < posts.json to fail. As a workaround, you can usemongoimport -d blog -c posts < posts.json -batchSize 1.If you have any difficulty using MongoProc, [...]

The solution to HOMEWORK 4.1 M101JS: MongoDB FOR NODE.JS DEVELOPERS Suppose you have a collection with the following indexes: > db.products.getIndexes() [ { "v" : 1, "key" : { "_id" : 1 }, "ns" : "store.products", "name" : "_id_" }, { "v" : 1, "key" : { "sku" : 1 }, "unique" : true, "ns" : [...]

Final: Question 6 Suppose you have a collection of students of the following form: { "_id" : ObjectId("50c598f582094fb5f92efb96"), "first_name" : "John", "last_name" : "Doe", "date_of_admission" : ISODate("2010-02-21T05:00:00Z"), "residence_hall" : "Fairweather", "has_car" : true, "student_id" : "2348023902", "current_classes" : [ "His343", "Math234", "Phy123", "Art232" ] } Now suppose that basic inserts into the collection, which only [...]

Final: Question 4 Enhancing the Blog to support viewers liking certain commentsIn this problem, you will be enhancing the blog project to support users liking certain comments and the like counts showing up in the permalink page. Start by downloading Final4.zip and posts.json from the Download Handout link and loading up the blog dataset posts.json. [...]

Final: Question 3 In this problem, you will update a document in the Enron dataset to illustrate your mastery of updating documents from the shell. Please add the email address "mrpotatohead@mongodb.com" to the list of addresses in the "headers. To" array for the document with "headers.Message-ID" of "<8147308.1075851042335.JavaMail.evans@thyme>" After you have completed that task, please [...]

Final: Question 2 Please use the Enron dataset you imported for the previous problem. For this question, you will use the aggregation framework to figure out pairs of people that tend to communicate a lot. To do this, you will need to unwind the To list for each message. This problem is a little tricky [...]