1. Evolution of Mongodb
An introduction to what and why is mongodb

2. What is Mongodb ?
 Humongous
 {name:mongodb,type:db}
 10gen

3. What is Mongodb ?
 Non-relational
 Json/bson document store
 Nosql What is it?
 Schemaless , what is schema less? And why?

4. Agenda
 Why mongodb is required or where mongodb fits in
 Mongodb schemaless architecture
 Mongodb and RDBMS
 Scalability and performance
 Summary

5. Why Mongodb ?
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Where mongodb fits in
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6. Why Mongodb ?
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 Relational based DBMS is not known to be scalable
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 You require high end hardware architecture for performance
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 RDBMS data storage is not easy flexible
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7. Why Mongodb ?
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Relational db is not known to be very scalable and performance oriented unless if
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provide its rich functionality but wont be performance oriented and hence not much
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Some softwares like Memcache,redis or other key-value store is very good when it
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comes to performance and scalability but often they provide a limited functionality
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8. Why Mongodb ?
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Mongodb fills the gap between these two so its very performance oriented and scalable
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and have rich set of functionality too that often comparable to what RDMBS
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It does deliberately though omit few functionality of RDBMS in order to Outline Level
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Mongo db does not support Joins , Transactions and schema less
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9. Schema less
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Mongodb is schema less
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10. Schema less
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And one of reason for it is being schemaless
Is It stores data as json document or in other word as javascript object and object
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Often is schemaless one object can have different data andThird Outline Level
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Why object is being stored instead of data? 
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11. Schema less
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Why object is being stored instead of data?
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12. Schema less
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Why object is being stored instead of data?
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One size doesn’t fits all Third Outline Level
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We often need to interact with data objects in programs instead of data itself
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No ORM required
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Object and its hierarchy is more closer to programming model. Sixth Outline Level
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13. Schema less
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Schemaless architecture of database
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Objects are different to each other 
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Agility − Fourth Outline Level
No Alter table 
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db.students.save({name:“user1”,type:”student”})
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db.students.save({name:”user2”,type:”student”,favsubjects:[ ‘math’,’english’] })
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We can change schema of existing document too
db.students.save({name:“user1”,type:”student”,favcolors:[‘blue’,’purple’]})
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14. Mongodb & RDMBS
 Is mongodb replacement for RDBMS?
 When you should consider mongodb over RDBMS?
 What are pros and cons using mongodb?

15. Mongodb & RDMBS
 What are pros and cons using mongodb?
Tradeoffs
Mongodb provides:
− Flexibility
− Performance
− Scalability
Does not support :
Joins
Transactions

16. Mongodb & RDMBS
 Why join and transactions are not being supported?
Cos it has to be scalable and performance oriented. Using
join will limit its scalability and transactions affect
performance.
Transactions often not required until you are building
some secure , real time app which is very transactional.
Though mongodb does provides atomic operations but its
currently limited to one document only.

17. Mongodb & RDMBS
 How mongodb exists without join?

18. Mongodb & RDMBS
 How mongodb exists without join?
And the answer is it support embed.
Mongodb document being json fundamentally , can have
embedded sub-documents with it.
So a json document fundamentally comprised of a
dictionary can have another array and even other
dictionaries embedded to it.
e.g :
{
post : “abc”,

19. Mongodb & RDMBS
Embed ? Isn't it violating normal form rules?
It Does and it could be beneficial or harmful depends on
when you are using it.
When to embed or not?

20. Mongodb & RDMBS
When to embed or not?
When to embed:
. If it is being often accessed with main document, then
embed it.
. If change to embedded document is most likely not to be
done
When not to embed:
If size of document is going to be over 16 mb.
{

21. Mongodb & RDMBS
• When you should consider mongodb over RDBMS?
If your DB is 3NF and you don’t do any joins (you’re just
selecting a bunch of tables and putting all the objects
together, AKA what most people do in a web app),
MongoDB would probably for you.

22. Mongodb & RDMBS
 Is mongodb replacement for RDBMS?
Its not when your application fall in below Categories:
 High transactional applications
 Ad-hoc business intelligence
 Problems which require a sql solution

23. Scalability and performance
Scalability:
 Bigdata
 Replications
 Fault-tolerence
 High-availability
 MongoDB provides two types of scaling.
 Read scaling: is provided by Replica Sets.
 Write scaling is provided by Sharding.

24. Scalability and performance
Scalability:
Replica sets:
A MongoDB replica set is a cluster of mongod
instances that replicate amongst one another and ensure
automated failover
Sharding:
MongoDB’s sharding system allows users to partition a
collection within a database to distribute the collection’s
documents across a number of mongod instances or shards
, sharding is often termed as load-balancing feature of mongodb
to ensure high traffic insert wouldn’t affect performance.

25. Scalability and performance
Mongodb and performance:
Is it comparable to RDMBS? Mysql?
Point is it has got all and sometimes even more, that
required for being a performance oriented dbms.
and it depends on how you design your db.
 Support indexes
 Support distributed db architecture
Most of the case mongodb is faster and requires less
memory look up round then RDBMS to fetch records.

26. Summary
Mongodb is fast, reliable, scalable database management
system. The main advantages as mentioned before are
flexibility, scalability and performance , it is promising yet
has some tradeoffs and therefore currently cannot replace
the RDBMs for each situation. It is a different type of
database which can be a solution, based on the
requirements of the situation. It will not replace RDBMs
databases and it might run well side-by-side in the future

27. References
 stackoverflow
 10 gen wiki
 Google

28. Thank you
Anshuman Ravi,
10gen certified mongodb
developer.