Confessions of a relational addict

Confessions of a relational addict
Chandra Patni

Twitter @cpatni

Architecture

http://www.seas.upenn.edu/~zives/03f/cis550/codd.pdf Volume 13 / Number 6 / June 1970 Volume 13 / Number 6 / June 1970

Promise of ACID
Atomicity
Consistency
Isolation
Durability

READ COMMITTED may block

ANSI/ISO SQL...
READ UNCOMMITTED to allow for non-blocking reads

But allowed dirty reads...

Isolation. Really?

Locking Lock Escalation Read Lock Write Lock Table Lock

MVCC
For transactional memory

Readers don’t block readers
Readers don’t block writers
Writers don’t block writers
Writers block writers (serialized)

Living in a bliss

Until...

need redundancy

scale reads

scale writes

horizontally

Solutions...

replication to scale reads

cache through writes

expensive solution for redundancy

mongodb

Distributed database from ground up

replication in a minute (HA)

built-in cache through writes

replicate if you care about your data

sharding (scale out)

Effective Design

Domain objects rarely fit in a table row

join to assemble domain objects

mongo documents as pre-assembled domain objects

in place updates ($set, $push)

New hotness

Multikeys

Map reduce map = function () { for (var i = 0; i < this.tags.length; i++) { emit(this.tags[i], this.state == "published" ? 1 : 0); } } reduce = function (key, values) { var total = 0; for (var i = 0; i < values.length; i++) { total += values[i]; } return total; }

Capped collections

Geospatial

GridFS

Rubber meets the road

Realtime Dashboard

Realtime Dashboard
Realtime stats for 1 sec, 5 secs, 15 secs
4K updates per second
pywebsocket

IGN Media: Editorial Generated Content

Content in Mongodb
Master/slave over filer for instant backups
100 ops
Ruby on Rails backend
MongoMapper
Integrate Solr Search with MongoMapper: http://github.com/tsxn26/customized-mongomapper-search
XML/JSON serialization: http://github.com/rubyorchard/mongomapper

RESTful API

Game Schema Design
Rapid Schema Revision
Optimize canonical use-case

IGN Social: User Generated Content
Manish Pandit

Activity Streams
3M documents @10-15 qps, @5 updates/sec
Moving to activity propagation: 4 documents for every user, i.e. a total of 2M documents with arrays of 500 activities each
Move to replica sets on 1.7

Meta+Level Games

Shadelight
Data in MongoDB and Redis
Replicated in real-time to slave servers
Master and slave are in different colo
Ben Myles wrote awesome library called MongoMatic http://mongomatic.com /

Mongomatic
Ruby datamapper for MongoDB
Simple and embraces MongoDB
Shadelight and Mongo Machine ( http://mongomachine.com/ ) use it

We’re hiring
http://corp.ign.com /
http://labs.ign.com /

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Confessions of a relational addict

by Chandra Patni

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