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
   

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2. Jorge Silva
   Developer Evangelist @ RethinkDB
   @thejsj
   

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3. Preface
   Why is realtime important?
   

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4. Realtime apps
   

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5. Realtime apps
   

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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
   

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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
   

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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
   

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9. Introduction
   What is RethinkDB?
   

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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
    

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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
    

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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
    

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13. Push Database
    RethinkDB is an excellent database for:
    • Collaborative web and mobile apps
    • Multiplayer games
    • Streaming analytics apps
    • Connected devices
    

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14. Introduction to ReQL
    RethinkDB Query Language
    

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

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

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

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

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

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

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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"})
    

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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
    

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23. Realtime Updates
    Working with Changefeeds
    

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24. Subscribe to change notifications
    on database queries
    Changefeeds
    

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

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26. 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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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
    }
    

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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',
    ...
    }
    }
    

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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'
    }
    }
    

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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:
    

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31. Questions
    http://questions.rethinkdb.com
    

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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
    

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33. Questions
    • RethinkDB website:

    http://rethinkdb.com
    • Install RethinkDB:

    http://rethinkdb.com/install/
    • Email me: jorge@rethinkdb.com
    • Tweet: @thejsj, @rethinkdb
    

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