RethinkDB The database for the realtime web Big Data Meetup Utah Salt Lake City, Utah May 6, 2015

Jorge Silva @thejsj Developer Evangelist @ RethinkDB

Introduction What is RethinkDB?

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

Built for Realtime Apps • Subscribe to change notifications from database queries • No more polling — the database pushes changes to your app • Reduce the amount of plumbing needed to stream live updates

RethinkDB Structure Database → Table → Document MySQL: Database → Table → Row MongoDB: Database → Collection → Document

Sample Document { "name": "Will Riker", "position": "Commander", "height": 193, "birthdate": Mon Aug 19 2335, "ships": [ { "name": "USS Pegasus" }, { "name": "USS Potemkin" }, { "name": "USS Enterprise" }, ], ... }

Introduction to ReQL RethinkDB Query Language

Introduction to ReQL • ReQL embeds natively into your programming language • Compose ReQL queries by chaining commands

Anatomy of a ReQL Query r.table("users") .pluck("last_name") .distinct().count() Number of unique last names

Anatomy of a ReQL Query r.table("users") .pluck("last_name") .distinct().count() Access a database table

Anatomy of a ReQL Query r.table("users") .pluck("last_name") .distinct().count() Isolate a document property

Anatomy of a ReQL Query r.table("users") .pluck("last_name") .distinct().count() Consolidate duplicate values

Anatomy of a ReQL Query r.table("users") .pluck("last_name") .distinct().count() Display the number of items

Sample ReQL Queries r.table("users") .filter(r.row("age").gt(30)) r.table("users") .pluck("last_name") .distinct().count() r.table("fellowship") .filter({species: "hobbit"}) .update({species: "halfling"})

ReQL Commands • Transformations: map, orderBy, skip, limit, slice • Aggregations: group, reduce, count, sum, avg, min, max, distinct, contains • Documents: row, pluck, without, merge, append, difference, keys, hasFields, spliceAt • Writing: insert, update, replace, delete • Control: forEach, range, branch, do, coerceTo, expr

Running Queries http://bit.ly/1JQ8imw

Understanding ReQL • Anonymous function must return a valid ReQL expression • Client driver translates ReQL queries into wire protocol • In JS use e.g. the mul and gt commands instead of the normal operators

Additional ReQL Features • Geospatial indexing for location- based queries • Date and time functions for time data • Support for storing binary objects

Realtime Updates Working with Changefeeds

Subscribe to change notifications on database queries Changefeeds

Changefeeds Example http://realtime-photo.thejsj.com/

r.table("users").changes() Track changes on the users table Changefeeds

Changefeeds • The changes command returns a cursor that receives updates • Each update includes the new and old value of the modified record

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 }

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', ... } }

Changefeeds r.table("users").changes() r.table("users") .get("362ae837-2e29-4695-adef-4fa415138f90") .update({name: "Bobbby"}) Changefeed output: { new_val: { id: '362ae837-2e29-4695-adef-4fa415138f90', name: 'Bobby' }, old_val: { id: '362ae837-2e29-4695-adef-4fa415138f90', name: 'Bob' } }

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:

Changefeeds r.table("table").get(ID).changes() r.table("table").getAll(ID).changes() r.table("table").between(X, Y).changes() r.table("table").filter(CONDITION).changes() r.table("table").union(ID).changes() r.table("table").map(FUNCTION).changes() r.table("table").min(INDEX).changes() r.table("table").max(INDEX).changes() r.table("table").orderBy(INDEX) .limit(N).changes() Commands that currently work with changefeeds:

Using Changefeeds

Cluster Configuration Sharding and replication

Sharding and Replication • RethinkDB is designed for clustering and easy scalability • To add a new server to the cluster, just launch it with the join option • Configure sharding and replication per table • Any feature that works with a single database will work in a sharded cluster

Add a Server to a Cluster $ rethinkdb --join server:29015 >

Clustering

Additional Resources • RethinkDB website:
 http://rethinkdb.com • RethinkDB cookbook:
 http://rethinkdb.com/docs/cookbook • RethinkDB installation:
 http://rethinkdb.com/docs/install/