2. Why MongoDB?
• Easy to use nosql
• Good for web projects
• Popular
• High performance (No joins and embedding makes reads and writes fast)
• High availability (Replicated servers with automatic master failover)
• Easy scalability (Automatic sharding)
3. What’s MongoDB good for?
• Account and user profiles: can store arrays of addresses with ease
• CMS: the flexible schema of MongoDB is great for heterogeneous collections of content types
• Form data: MongoDB makes it easy to evolve structure of form data over time
• Blogs / user-generated content: can keep data with complex relationships together in one object
• Messaging: vary message meta-data easily per message or message type without needing to
maintain separate collections or schemas
• System configuration: just a nice object graph of configuration values, which is very natural in
MongoDB
• Log data of any kind: structured log data is the future
• Graphs: just objects and pointers – a perfect fit
• Location based data: MongoDB understands geo-spatial coordinates and natively supports geo-
spatial indexing
http://blog.mongolab.com/2012/08/why-is-mongodb-wildly-popular/
4. The Modern Need From Databases
• Easy to use when project is small
• Developing schema less
• When we need scale it must be easy and cheap
• No data loss
• High Availability
6. What is BSON?
• MongoDB uses BSON as the data storage and network transfer format
for "documents".
• Short for Binary JSON
• http://bsonspec.org/
• http://www.mongodb.org/display/DOCS/BSON
7. Working with Entity Objects
• Things can be really easy for you if you follow these rules for your
entities
• Has a public no-argument constructor
• Has a public get set property for each value you want to have serialized
9. Write Concern
• Acknowledged
• Write operations that use this write concern will wait for acknowledgement from the primary
server before returning.
• Unacknowledged
• Write operations that use this write concern will return as soon as the message is written to
the socket.
• Journaled
• Exceptions are raised for network issues, and server errors; the write operation waits for the
server to group commit to the journal file on disk.
• Replica Acknowledged
• Exceptions are raised for network issues, and server errors; waits for at least 2 servers for the
write operation.
http://docs.mongodb.org/manual/core/write-concern/
http://api.mongodb.org/java/current/com/mongodb/WriteConcern.html
https://github.com/mongodb/mongo-csharp-driver/blob/master/MongoDB.Driver/WriteConcern.cs
10. Journaling
• Process starts with private view
• Private view writes to journal
• Journal updates shared view
• Shared view updates private view
• Shared view flushes data to disk
http://www.kchodorow.com/blog/2012/10/04/how-mongodbs-journaling-works/
12. A tip for better indexing
• Run mongodb with notablescan parameter and be sure your your
queries are not making full table scans...
• You get exceptions if a query needs a table scan, it gives you a chance to fix
your indexes on development time.
14. Transaction
• MongoDB does not support transactions.
• It is good to use relational databases (oracle, sql server) for this
purpose
• If you are stuck in a situation that needs transactions with MongoDB
you must implement it by your self.
• http://docs.mongodb.org/manual/tutorial/perform-two-phase-commits/
• https://github.com/rystsov/mongodb-transaction-example
16. Replication
• Copies of your data for data safety
• Asynchronous replication
• Master - Slave model
• Not master-master, when your data change
there are times that you only have one master…
• Statement based
• For example, insert statement send to the
replica and will run there…
• Driver is replica set aware,
• Connection to replica set
mongodb://server1,server2:27017,server2:27018
17. Sharding (partitioning)
• MongoDB does range based
partitioning
• Name begins with A, B-E, F-H ….
• Shardkey is important!
• Bad shard key choice can cause
too many split and merge
operations on chunks
mongod
mongod
mongod
Replicaset
mongod
mongod
mongod
Replicaset
S1 S2
mongos
mongod
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mongod
Config
Server
Client
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