Push databases: A better way to build realtime apps

Transcript

1. Push databases A better way to build realtime apps Bay Area OpenSource Palo Alto, CA July 8, 2015
2. Jorge Silva Developer Evangelist @ RethinkDB @thejsj
3. Preface Why is realtime important?
4. Realtime apps
5. Realtime apps
6. Realtime apps • More and more apps are built to be realtime • Users have come to want and expect this behavior in their apps • Building realtime apps is hard
7. Building realtime apps is hard • You can keep everything in a single server • You can poll the database to keep track of updates • You can publish updates through 
 a message broker
8. Building realtime apps is hard • All solutions present a tradeoff between scalability and complexity • It’s hard to keep track of state in 
 realtime architectures
9. Introduction What is RethinkDB?
10. What is RethinkDB? • Open source database for building realtime web applications • NoSQL database that stores schemaless JSON documents • Distributed database that is easy to scale
11. Push Database • Subscribe to change notifications from database queries (changefeeds) • No more polling — the database pushes changes to your app • Reduce the amount of plumbing needed to stream live updates
12. Push Database • Having your database push changes keeps your database as the central source of truth • Having a central source of truth simplifies your architecture
13. Push Database RethinkDB is an excellent database for: • Collaborative web and mobile apps • Multiplayer games • Streaming analytics apps • Connected devices
14. Introduction to ReQL RethinkDB Query Language
15. Introduction to ReQL • ReQL embeds natively into your programming language • Compose ReQL queries by chaining commands
16. Anatomy of a ReQL Query r.table("users") .pluck("last_name") .distinct().count() Number of unique last names
17. Anatomy of a ReQL Query r.table("users") .pluck("last_name") .distinct().count() Access a database table
18. Anatomy of a ReQL Query r.table("users") .pluck("last_name") .distinct().count() Isolate a document property
19. Anatomy of a ReQL Query r.table("users") .pluck("last_name") .distinct().count() Consolidate duplicate values
20. Anatomy of a ReQL Query r.table("users") .pluck("last_name") .distinct().count() Display the number of items
21. Sample ReQL Queries r.table("users") .filter(r.row("age").gt(30)) r.table(“post") .eqJoin(“uId”, r.table(“users”)) .zip() r.table("fellowship") .filter({species: "hobbit"}) .update({species: "halfling"})
22. Additional ReQL Features • Geospatial indexing for location- based queries • Date and time functions • Support for storing binary objects • Execute http requests using r.http
23. Realtime Updates Working with Changefeeds
24. Subscribe to change notifications on database queries Changefeeds
25. r.table("users").changes() Track changes on the users table Changefeeds
26. Changefeeds • The changes command returns a cursor that receives updates • Each update includes the new and old value of the modified record
27. Changefeeds r.table("users").changes() r.table("users") .insert({name: "Bob"}) Changefeed output: { new_val: { id: '362ae837-2e29-4695-adef-4fa415138f90', name: 'Bob', ... }, old_val: null }
28. Changefeeds r.table("users").changes() r.table("users") .filter({name: "Bob"}).delete() Changefeed output: { new_val: null, old_val: { id: '362ae837-2e29-4695-adef-4fa415138f90', name: 'Bob', ... } }
29. Changefeeds r.table("users").changes() r.table("users") .get("362ae837-2e29-4695-adef-4fa415138f90") .update({name: "Bobby"}) Changefeed output: { new_val: { id: '362ae837-2e29-4695-adef-4fa415138f90', name: 'Bobby' }, old_val: { id: '362ae837-2e29-4695-adef-4fa415138f90', name: 'Bob' } }
30. Changefeeds r.table("players") .orderBy({index: r.desc("score")}) .limit(3).changes() Track top three players by score Chain the changes command to an actual ReQL query:
31. Questions http://questions.rethinkdb.com
32. Summary • Keeping track of state in realtime apps is hard • RethinkDB solves this problem by pushing changes to your app • In the future, we'll see more database that use the push model
33. Questions • RethinkDB website:
 http://rethinkdb.com • Install RethinkDB:
 http://rethinkdb.com/install/ • Email me: jorge@rethinkdb.com • Tweet: @thejsj, @rethinkdb