NoSQL: what's under the hood?

what’s under the hood?
Aleksey Solntsev

The Digital Universe

Some facts

What’s they have in common?
Performance
Scalability
Price

RDBMS
ACID doesn’t scale well horizontally
Shardingbreaks relations
Joins are inefficient
Transactions overhead
Schema is not flexible

ACID
Atomicity
Consistency
Isolation
Durability

NoSQL: Not Only SQL
Non-Relational
Distributed
Scaling Out Scalability
Schema-less/Schema-free
Eventual Consistency

We need to scale!

Replication aka RAID1

Sharding aka RAID0

CAP theorem (Brewer's theorem)

ACID
Atomicity
Consistency
Isolation
Durability
BASE
Basically Available
Soft State
Eventually Consistent

NoSQL Taxonomy
Key Value / Tuple Store
Eventually Consistent Key Value Store
Wide Column Store / Column Families
Document Oriented
XML Databases
Object Databases
Graph Databases

Focus on scaling to huge amounts of data
Designed to handle massive load

Distributed hash table

Partitioning 1/2

Partitioning 2/2

Primitive API
CRUD

Map/Reduce for aggregation
map(String filename, String document) {
List<String> T = tokenize(document);
for each token in T {
emit ((String)token, (Integer) 1);
}
}
reduce(String token, List<Integer> values) {
Integer sum = 0;
for each value in values {
sum = sum + value;
}
emit ((String)token, (Integer) sum);
}

MapReduceи Hadoop?

Single infinitely large table
Each rows can have different number of columns

Column

SuperColumn

ColumnFamily

Keyspace

API
No standards:
Structure manipulation
Cluster administration
Query language

Semi-structured complex documents
Document versioning
Support references between documents

{
"_id" : ObjectId("497ce96f395f2f052a494fd4"),
"title" : "Awesome Blog Post",
"body" : "Text text text text, text text text ...",
"created": "Tue, 3 Jan 2011 11:13:56 GMT",
"publishDate" : "Tue, 21 Jan 2011 20:42:47 GMT",
"tags" : [ "css", "javascipt", "jquery" ],
"comments" : [
{
"name" : "Kelly Glover"
"created" : "Tue, 22 Jan 2011 2:22:32 GMT",
"text" : "This is a very good ..."
},
{
"name" : "Pat Tally"
"created" : "Tue, 22 Jan 2011 4:54:41 GMT",
"text" : "Thanks!",
"admin" : true
} ],
"shortUrl" : "awesome-blog-post"
}

Advances Query API
Find by example
db.stat.find({clicks: {$gt: 10} });
Find & sort
db.users.find({}).sort({name: 1});
Skip & limit
db.users.find().skip(20).limit(10);

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NoSQL: what's under the hood?

by Aleksey Solntsev on Oct 12, 2011

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NoSQL: what’s under the hood? — Presentation Transcript