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Introduction to Big Data and NoSQL. SQL Azure Saturday April, 21, 2012. Don Demsak Advisory Solutions Architect EMC Consulting www.donxml.com. Meet Don. Advisory Solutions Architect EMC Consulting Application Architecture, Development & Design DonXml.com, Twitter: donxml
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Introduction to Big Data and NoSQL SQL Azure Saturday April, 21, 2012 Don Demsak Advisory Solutions Architect EMC Consulting www.donxml.com
Meet Don • Advisory Solutions Architect • EMC Consulting • Application Architecture, Development & Design • DonXml.com, Twitter: donxml • Email – don@donxml.com • SlideShare - http://www.slideshare.net/dondemsak
How did we get here? • Expensive • Processors • Disk space • Memory • Operating Systems • Software • Programmers • Monoculture • Limit CPU cycles • Limit disk space • Limit memory • Limited OS Development • Limited Software • Programmers • Mono-lingual • Mono-persistence
Typical RDBMS Implementations • Fixed table schemas • Small but frequent reads/writes • Large batch transactions • Focus on ACID • Atomicity • Consistency • Isolation • Durability
2nd Step – Table Partitioning • p1 p2 p3 Database
3rd Step – Database Partitioning Database Web Tier B/L Tier Browser • Customer #1 Database Web Tier B/L Tier Browser • Customer #2 Database Web Tier B/L Tier Browser • Customer #3
4th Step – Move to the cloud? SQL Azure Federation Web Tier B/L Tier Browser • Customer #1 SQL Azure Federation Web Tier B/L Tier Browser • Customer #2 SQL Azure Federation Web Tier B/L Tier Browser • Customer #3
Where Did NoSQL Originate? • 1998 - Carlo Strozzi • NoSQL project - lightweight open-source relational DB with no SQL interface • 2009 - Eric Evans & Johan Oskarsson of Last.fm wanted to organize an event to discuss open-source distributed databases
NoSQL (loose) Definition • (often) Open source • Non-relational • Distributed • (often) don’t guarantee ACID
Atlanta 2009 • No:sql(east) conference • select fun, profit from real_world where relational=false • Billed as “conference of no-reldatastores”
Document Store • Apache Jackrabbit • CouchDB • MongoDB • SimpleDB • XML Databases • MarkLogic Server • eXist.
Document? • Okay think of a web page... • Relational model requires column/tag • Lots of empty columns • Wasted space • Document model just stores the pages as is • Saves on space • Very flexible.
Graph Storage • AllegroGraph • Core Data • Neo4j • DEX • FlockDB • Microsoft Trinity (research project) • http://research.microsoft.com/en-us/projects/trinity/
What’s a graph? • Graph consists of • Node (‘stations’ of the graph) • Edges (lines between them) • FlockDB • Created by the Twitter folks • Nodes = Users • Edges = Nature of relationship between nodes.
Key/Value Stores • On disk • Cache in Ram • Eventually Consistent • Weak Definition • “If no updates occur for a period, eventually all updates will propagate through the system and all replicas will be consistent” • Strong Definition • “for a given update and a given replica eventually either the update reaches the replica or the replica retires” • Ordered • Distributed Hash Table allows lexicographical processing
Key/Value Examples • Azure AppFabricCache • Memcache-d • VMWare vFabricGemFire
Object Databases • Db4o • GemStone/S • InterSystemsCaché • Objectivity/DB • ZODB
Tabular • BigTable • Mnesia • Hbase • Hypertable • Azure Table Storage • SQL Server 2012
Big Data Definition • Volumes & volumes of data • Unstructured • Semi-structured • Not suited for Relational Databases • Often utilizes MapReduce frameworks
Big Data Examples • Cassandra • Hadoop • Greenplum • Azure Storage • EMC Atmos • Amazon S3 • SQL Azure (with Federations support)
Real World Example • Twitter • The challenges • Needs to store many graphs • Who you are following • Who’s following you • Who you receive phone notifications from etc • To deliver a tweet requires rapid paging of followers • Heavy write load as followers are added and removed • Set arithmetic for @mentions (intersection of users).
What did they try? • Started with Relational Databases • Tried Key-Value storage of denormalized lists • Did it work? • Nope • Either good at • Handling the write load • Or paging large amounts of data • But not both
What did they need? • Simplest possible thing that would work • Allow for horizontal partitioning • Allow write operations to • Arrive out of order • Or be processed more than once • Failures should result in redundant work • Not lost work!
The Result was FlockDB • Stores graph data • Not optimized for graph traversal operations • Optimized for large adjacency lists • List of all edges in a graph • Key is the edge value a set of the node end points • Optimized for fast read and write • Optimized for page-able set arithmetic.
How Does it Work? • Stores graphs as sets of edges between nodes • Data is partitioned by node • All queries can be answered by a single partition • Write operations are idempotent • Can be applied multiple times without changing the result • And commutative • Changing the order of operands doesn’t change the result.
ACID • Atomicity • All or Nothing • Consistency • Valid according to all defined rules • Isolation • No transaction should be able to interfere with another transaction • Durability • Once a transaction has been committed, it will remain so, even in the event of power loss, crashes, or errors
BASE • Basically Available • High availability but not always consistent • Soft state • Background cleanup mechanism • Eventual consistency • Given a sufficiently long period of time over which no changes are sent, all updates can be expected to propagate eventually through the system and all the replicas will be consistent.
Traditional (relational) Approach Transactional Data Store Data Warehouse
Big Data Approach • MapReduce Pattern/Framework • an Input Reader • Map Function – To transform to a common shape (format) • a partition function • a compare function • Reduce Function • an Output Writer
MongoDB Example > // map function > m = function(){ ... this.tags.forEach( ... function(z){ ... emit( z , { count : 1 } ); ... } ... ); ...}; > // reduce function > r = function( key , values ){ ... var total = 0; ... for ( var i=0; i<values.length; i++ ) ... total += values[i].count; ... return { count : total }; ...}; > // execute > res = db.things.mapReduce(m, r, { out : "myoutput" } );
Big Data on Azure • Azure Table Storage • Azure Service Bus • SQL Azure Federations • MongoDB on Azure • http://www.mongodb.org/display/DOCS/MongoDB+on+Azure • Hadoop on Azure • https://www.hadooponazure.com/
Using Azure for Computing Data Worker Data Data Worker Client Master Sockets Job/Task Scheduler Worker Data
Moving to Event Based Architecture Web Role Worker Role Web Role Worker Role Web Role Worker Role Req Req Req Queue Web Role Worker Role Web Role • Monitor queue • length against user’s expectations Worker Role Web Role Worker Role
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