Luca Bonmassar

[Anti]Patterns with NoSQL

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NoSQL vs. SQL

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NoSQL / NoAgenda

No specific NoSQL technologies (document, key/value, ...)

No specific NoSQL db features (sharding, replication, ...)

No specific ...

...

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Does it solve my problem?

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Does it solve my problem?

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Does it solve my problem?

But what is your problem?

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Does it solve my problem?

But what is your problem?

NoSQL fragmentation (like NoCloud, NoJava, NoMicrosoft, ...)

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[Anti]PatternsThe “dynamic” website

Data mapping

The Alien

The binary Alien

The SQLQueue

Overnormalized

Unpredictable tomorrow

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Who am I?

Passionate about technology

Favorite topics: Cloud, Virtualization, NoSQL

Gamification fan! (or fun?)

The “dynamic” website

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The “dynamic” website

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The “dynamic” website

I have a website

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The “dynamic” website

I have a website

Dynamic contents everywhere

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The “dynamic” website

I have a website

Dynamic contents everywhere

High DB load

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The “dynamic” website

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The “dynamic” website

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The “dynamic” website

SELECT COUNT(###) WHERE ...

SELECT COUNT(###) WHERE ...

SELECT COUNT(###) WHERE ...

SELECT username FROM users WHERE

sessionid = ###

SELECT avatar.* FROM users WHERE ...

SELECT users.*, count(distinct puzzle_id) FROM submissions JOIN users on submissions.user_id = users.id where submissions.current_state =

"succeeded" ...

SELECT COUNT("submissions"."puzzle_id") FROM "submissions" WHERE (puzzle_id IS

NOT NULL) AND (user_id IS NOT NULL) GROUP BY puzzle_id ...

SELECT username FROM users WHERE

sessionid = ###

SELECT * FROM submissions WHERE ...

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The “dynamic” website

SELECT COUNT(###) WHERE ...

SELECT COUNT(###) WHERE ...

SELECT COUNT(###) WHERE ...

SELECT username FROM users WHERE

sessionid = ###

SELECT avatar.* FROM users WHERE ...

SELECT users.*, count(distinct puzzle_id) FROM submissions JOIN users on submissions.user_id = users.id where submissions.current_state =

"succeeded" ...

SELECT COUNT("submissions"."puzzle_id") FROM "submissions" WHERE (puzzle_id IS

NOT NULL) AND (user_id IS NOT NULL) GROUP BY puzzle_id ...

SELECT username FROM users WHERE

sessionid = ###

SELECT * FROM submissions WHERE ...

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The “dynamic” website

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The “dynamic” website

SELECT COUNT(###) WHERE ...

SELECT COUNT(###) WHERE ...

SELECT COUNT(###) WHERE ...

SELECT username FROM users WHERE

sessionid = ###

SELECT avatar.* FROM users WHERE ...

SELECT users.*, count(distinct puzzle_id) FROM submissions JOIN users on submissions.user_id = users.id where submissions.current_state =

"succeeded" ...

SELECT COUNT("submissions"."puzzle_id") FROM "submissions" WHERE (puzzle_id IS

NOT NULL) AND (user_id IS NOT NULL) GROUP BY puzzle_id ...

SELECT username FROM users WHERE

sessionid = ###

SELECT * FROM submissions WHERE ...

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The “dynamic” website

Is it that dynamic?

Are there any data structures that fit better than relational?

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Cache, Cache, Cache

Use Ad-Hoc Caching (e.g. Rails Caching)

SQL Table as cache

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SQL Table as Cache

When you use SQL Table as Cache, a kitten somewhere dies

Use Memcache, MemcacheDB, Redis

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Better tools?

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Rethink data structures

SELECT COUNT(*) ...SELECT COUNT(*) ...SELECT COUNT(*) ...

submitted++passed++failed++

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Rethink data structures

SELECT *, count(distinct ...) FROM submissions JOIN users on ... where submissions.current_state = "succeeded" ...

List(5)List.add / List.replace

Data mapping

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Data mapping

An original idea: we need a newsfeed!

Users can comment on feed items

Users can reply to comments

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What the customer is looking for

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What the developer is thinking about

But how to ...

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Eureka!

The item has a feed_id and a parent_id

You have now a navigable SQL data structure!

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Data mapping - alternatives

Do not try this at home! (or any office)

A document db can help

{ feed : 42, user : ‘luca.bonmassar’, data : ‘living the dream!’, comments : [{user : ‘jonny’ : ‘make sense!’ }] }

The Alien

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The Alien

A type of object stored in a relational database

No (or weak) relations with any other table

Stored in the db because the db == persistency

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User Settings

User preferences

user_id, data

Data as BLOB or TEXT

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The Alien

The Alien is a key/value entity

Use a key/value storage to store it

The binary Alien

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The binary Alien

Like the Alien, but the payload is pure binary data

Common solution to store “small” images

Even worse: Base64 encoded binary

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The binary Alien

Move the binary Alien to a binary content provider

S3 or Filesystem are good ones

Let the webserver access/serve them directly

The SQLQueue

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The SQLQueue

Distributed components need to exchange data

Producers / Consumers

Backlog of work to be completed

SQL database (== persistency) as persistent queue

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Mail delivery

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Mail delivery

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Mail delivery

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Mail delivery

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The SQLQueue

No “relations”, like the Alien

Simulating a Queue using AUTO_INCREMENT ids and transactions

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SQLQueue

In some countries, SQLQueue is considered a crime against software

Use message queues(Amazon SQS, MemcacheQ, StormMQ, RabbitMQ, ... )

Overnormalized

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Overnormalized

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Overnormalized

The process of organizing data to minimize redundancy

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Overnormalized

The process of organizing data to minimize redundancy

A larger schema is broken into smaller ones

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Overnormalized

The process of organizing data to minimize redundancy

A larger schema is broken into smaller ones

user_id, email

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Overnormalized

The process of organizing data to minimize redundancy

A larger schema is broken into smaller ones

user_id, email

user_id, phone_num

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Overnormalized

The process of organizing data to minimize redundancy

A larger schema is broken into smaller ones

user_id, email

user_id, phone_num

user_id, badge

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Overnormalized

PRO:

reduce redundancy

less overhead

each table scale separately

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OvernormalizedCons:

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OvernormalizedCons:

... JOIN... JOIN... JOIN... JOIN... JOIN... JOIN... JOIN...

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Overnormalized

Cache the normalized data

Denormalize / keep a replica of the denormalized view

Use document db or key/value storage for the replica

Unpredictable tomorrow

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Unpredictable tomorrow

You are now part of a new Agile(TM) project

You are Agile(TM), so:

No complete specs

No complete use cases

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How many wonderful things around me

A mobile App w/ internet backend

“Simple” use cases

User can log in

User can update their location

User can get all the many wonderful things they have around themselves

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How many wonderful things around me

Data Model:

User

Places

Aliens!!! Aliens!!! Aliens!!!

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...but sooner or later...

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How many wonderful things around me

Users can send/receive friendship invitations

Users can import FB friends, Twitter followers

Users can interact with messages, pokes

Users can check-in into places

Users can share their checkins with friends

...

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Unpredictable tomorrow

No silver bullets

Mix technologies

E.g. relational databases to handle relations

Migrations are painful, but always an option

One more thing

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Recap

Does it make sense with the relational paradigm?

Do I need a persistent storage or a relational database?

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Thanks! Any Questions?

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Contacts

luca@coderloop.com

linkedin.com/in/lucabonmassar

twitter.com/lucabonmassar

joind.in/talk/view/2939