ForwardJS - RethinkDB - Getting Started

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RethinkDB The database for the realtime web ForwardJS San Francisco, California July 30, 2015

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Jorge Silva @thejsj Developer Evangelist @ RethinkDB

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Schedule 1. What is RethinkDB? 2. RethinkDB query language 3. Working with changefeeds 4. Using RethinkDB with Node.js 5. Tutorial: Building a chat app

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Introduction What is RethinkDB?

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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

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Built for Realtime Apps • 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

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Built for Realtime Apps • Having your database push changes keeps your database as the central source of truth • Having a central source of truth simplifies your architecture

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Power and Convenience • Highly expressive query language • Relational features like table joins • Powerful admin UI with point- and-click cluster management

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

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

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Differences with Firebase • Firebase is a cloud service, not an open-source database • Because Firebase is not a database, it has limited querying abilities • Firebase is made to be queried from the browser

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Differences with MongoDB • RethinkDB supports joins and subqueries • MongoDB only supports the traditional query-response model. You can't subscribe to queries.

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Introduction to ReQL RethinkDB query language

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

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

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

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

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

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

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Sample ReQL Queries r.table("users") .filter(r.row("age").gt(30)) r.table(“posts") .eqJoin(“userId”, r.table(“users”)) .zip() r.table("posts") .filter({status: "draft"}) .update({status: "published"})

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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

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Understanding ReQL • All queries are executed by the database, not the client • Client driver translates ReQL queries into wire protocol • In JS use e.g. the mul and gt commands instead of the normal operators

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Additional ReQL Features • Geospatial indexing for location- based queries • Date and time functions • Support for storing binary objects • Execute http requests using r.http

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Installation http://rethinkdb.com/install

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Running Queries https://github.com/thejsj/rethinkdb-workshop

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Running Queries http://localhost:8080/ http://rethinkdb.thejsj.com:8080/

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Realtime Updates Working with Changefeeds

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Subscribe to change notifications on database queries Changefeeds

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

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

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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 }

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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', ... } }

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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' } }

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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:

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Changefeeds r.table("table").get(ID).changes() r.table("table").getAll(ID).changes() r.table("table").between(X, Y).changes() r.table("table").pluck(X, Y, Z).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:

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Using Changefeeds

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Building Web Apps Using RethinkDB in Node

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Client Driver • Use a RethinkDB client driver to access the database in your app • Oﬀicial drivers available for Ruby, Python, and JavaScript • Third-party drivers available for other languages like Go and Clojure

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> Client Driver Install the JS client driver from npm in your Node.js project: $ npm install rethinkdb --save

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Client Driver var r = require("rethinkdb"); r.connect().then(function(conn) { return r.table("users") .insert({name: “Bob”}).run(conn) .finally(function () { conn.close(); }); }).then(function(output) { console.log(output); }); Add Bob to the “users” table

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Client Driver var r = require("rethinkdb"); r.connect().then(function(conn) { return r.table("users") .insert({name: “Bob"}).run(conn) .finally(function () { conn.close(); }); }).then(function(output) { console.log(output); }); Import the RethinkDB module

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Using Changefeeds r.connect().then(function(conn) { return r.table("fellowship") .changes().run(conn); }) .then(function(cursor) { cursor.each(function(err, item) { console.log(item); }); }); Display every change on the “fellowship” table

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Using Changefeeds Attach a changefeed to the table r.connect().then(function(conn) { return r.table("fellowship") .changes().run(conn); }) .then(function(cursor) { cursor.each(function(err, item) { console.log(item); }); });

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Using Changefeeds Iterate over every value passed into the cursor r.connect().then(function(conn) { return r.table("fellowship") .changes().run(conn); }) .then(function(cursor) { cursor.each(function(err, item) { console.log(item); }); });

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Using Socket.io • Powerful framework for realtime client/server communication • Supports WebSockets, long polling, and other transports • Lets you send JSON messages between your app and frontend

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Socket.io (Server) var sockio = require("socket.io"); var app = require("express")(); var r = require("rethinkdb"); var io = sockio.listen(app.listen(8090)); r.connect().then(function(conn) { return r.table("players") .orderBy({index: r.desc("score")}) .limit(5).changes().run(conn); }) .then(function(cursor) { cursor.each(function(err, data) { io.sockets.emit("update", data); }); }); Broadcast score changes over Socket.io

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Socket.io (Client) Real-time web app var socket = io.connect(); socket.on("update", function(data) { console.log("Update:", data); }); Receive Socket.io updates on frontend

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Socket.io (Client) Real-time web app var socket = io.connect(); socket.on("update", function(data) { console.log("Update:", data); }); Load the Socket.io client script

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Socket.io (Client) Real-time web app var socket = io.connect(); socket.on("update", function(data) { console.log("Update:", data); }); Connect to the Socket.io server

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Socket.io (Client) Real-time web app var socket = io.connect(); socket.on("update", function(data) { console.log("Update:", data); }); Create handler for “update” messages

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Socket.io (Client) Real-time web app var socket = io.connect(); socket.on("update", function(data) { console.log("Update:", data); }); Display update in browser console

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Tutorial: Building a chat app

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#1: Clone the repository Clone From GitHub: git clone https://github.com/thejsj/ rethinkdb-workshop.git Download Tarball: https://github.com/thejsj/rethinkdb- workshop/tarball/master

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#2: Install Dependencies // Go to the project directory cd rethinkdb-workshop // Install dependencies npm install

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#3: Go to config/default.js Update your RethinkDB database configuration var config = { "rethinkdb": { "host": "localhost", // or rethinkdb.thejsj.com "port": 28015, "db" : "rethinkdb_workshop" // or GITHUB_HANDLE_rethinkdb_workshop },

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#4: Run Server // Start server npm run dev // or `node server`

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#4: Go to server/index.js Look for the comments in order to write the correct ReQL queries // Step 1 // Write a query

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Connections In this app, the `r` object contains a connection. r.table("messages").run(r.conn);

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#5: Switch database Connect to the following database, so we can all share messages var config = { "rethinkdb": { "host": "rethinkdb.thejsj.com", "port": 29015, "db" : "GITHUB_HANDLE_rethinkdb_workshop" },

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Next steps • Advanced Commands: `r.do`, `r.branch`, `r.forEach` • Map/Reduce queries • Indexes (multi, compound, index functions, geospatial) • Sharding and replication

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Questions • RethinkDB website:  http://rethinkdb.com • Install RethinkDB:  http://rethinkdb.com/install/ • Email me: jorge@rethinkdb.com • Tweet: @thejsj, @rethinkdb