Introduction to MongoDB. Uses example of a simple location-based application to introduce schema design, queries, updates, map-reduce, deployment

1. http://mongodb.org http://10gen.com Building applications with MongoDB – An introduction MongoNYC – June 7, 2011 Nosh Petigara [email_address] @noshinosh

3. Application Goals Places Check ins (1) Q: Current location A: Places near location (2) Add user generated content (3) Record user checkins (4) Stats about checkins

4. Documents doc1 = { _id: 4b97e62bf1d8c7152c9ccb74 , key1: value1, key2: value2, key3: {..., ..., ...}, key4: [..., ..., ] }

5. Collections doc1, doc2, doc3 Places Users Checkins doc3, doc4, doc5 doc6, doc7, doc8

6. Places v1 place1 = { name: "10gen HQ”, address: ”134 5 th Avenue 3 rd Floor”, city: "New York”, zip: "10011” } db.places.find({zip:”10011”}).limit(10)

7. Places v2 place1 = { name: "10gen HQ”, address: "17 West 18th Street 8th Floor”, city: "New York”, zip: "10011”, tags: [“business”, “recommended”] } db.places.find({zip:”10011”, tags:”business”})

8. Places v3 place1 = { name: "10gen HQ”, address: "17 West 18th Street 8th Floor”, city: "New York”, zip: "10011”, tags: [“business”, “cool place”], latlong: [40.0,72.0] } db.places.ensureIndex({latlong:”2d”}) db.places.find({latlong:{$near:[40,70]}})

9. Places v4 place1 = { name: "10gen HQ”, address: "17 West 18th Street 8th Floor”, city: "New York”, zip: "10011”, latlong: [40.0,72.0], tags: [“business”, “cool place”], tips: [ {user:"nosh", time:6/26/2010, tip:"stop by for office hours on Wednesdays from 4-6pm"}, {.....}, {.....} ] }

10. Querying your Places Creating your indexes db.places.ensureIndex({tags:1}) db.places.ensureIndex({name:1}) db.places.ensureIndex({latlong:”2d”}) Finding places: db.places.find({latlong:{$near:[40,70]}}) With regular expressions: db.places.find({name: /^ typeaheadstring /) By tag: db.places.find({tags: “business”})

11. Inserting and updating places Initial data load: db.places.insert(place1) Updating tips: db.places.update({name:"10gen HQ"}, {$push :{tips: {user:"nosh", time:6/26/2010, tip:"stop by for office hours on Wednesdays from 4-6"}}}}

12. Atomic Updates $set, $unset, $rename $push, $pop, $pull, $addToSet $inc

13. Application Goals Places Check ins (1) Q: Current location A: Places near location (2) Add user generated content (3) Record user checkins (4) Stats about checkins

14. Users user1 = { name: “nosh” email: “nosh@10gen.com”, . . . checkins: [ 4b97e62bf1d8c7152c9ccb74, 5a20e62bf1d8c736ab ] } checkins [] = ObjectId reference to checkin collection

15. Checkins checkin1 = { place: “10gen HQ”, ts: 6/7/2011 10:12:00, userId: <objectid of user> } Check-in = 2 ops Insert check in object [checkin collection] Update ($push) user object [user collection] Indexes: db.checkins.ensureIndex({place:1, ts:1}) db.checkins.ensureIndex({ts:1})

16. Application Goals Places Check ins (1) Q: Current location A: Places near location (2) Add user generated content (3) Record user checkins (4) Stats about checkins

17. Simple Stats db.checkins.find({place: “10gen HQ”) db.checkins.find({place: “10gen HQ”}) .sort({ts:-1}).limit(10) db.checkins.find({place: “10gen HQ”, ts: {$gt: midnight}}).count() db.checkins.find().sort(ts:-1)}.limit(50)

18. Stats with MapReduce mapFunc = function() { emit(this.place, 1);} reduceFunc = function(key, values) { return Array.sum(values); } db.checkins.mapReduce(mapFunc,reduceFunc, {query: {timestamp: {$gt:nowminus3hrs}}, out: “result”}) result = [{_id:”10gen HQ”, value: 17}, {…..}, {….}] db.result.find({ value: {$gt: 15}})

19. Application Goals Places Check ins (1) Q: Current location A: Places near location (2) Add user generated content (3) Record user checkins (4) Stats about checkins

24. MongoDB in Production