A quick look at MongoDB database

1. First steps with MongoDB

2. Index
When you should use NoSQL
When you should not use NoSQL
A quick look at MongoDB
Other features
Main scheme
Replication
Auto­sharding
Architecture
First steps

3. When should I use NoSQL?
Caching
High data amount
Horizontal scalability(without joins or complex
transactions)
The Slogan is ”not only SQL” and ”not only
NOSQL”

4. When should not I use
NoSQL
High transaction level
Business Intelligence
Problems that need relational queries

5. A quick look at MongoDB
Document database oriented (BSON)
Flexible scheme
Dinamic queries
Replication
Auto­sharding
Atomic operations
Full indexes

6. A quick look at MongoDB
Not relational
Distributed
Opensource
Horizontal scalability
Drivers for most known programming languages
Replication and automatic sharding
GridFS

7. Other features
Map Reduce
Queries are executed in parallel in all of the shards
Adittion and process of flexible data
Geospatial index
Find objects based on their geographical location

8. Basic scheme
Database Server
Shell
Sharding router
Mongod Mongo
Database server Interactive shell
Mongos
Sharding router

9. Replication
Master: mongod –master
Slave: mongod –source url:port or pasive –slavedelay
numberofseconds
Replica Sets
Full support in dealing with failures(recommended by each
shard)
You can have passive members that never will be masters.
Master­master
Only recommended for insert and delete queries by id.

10. Auto-sharding
Defined by a shard key
Response in dealing with failures is handled by each
replica set.
Queries map reduce could run in paralell between
many shards.
You can add servers as shards and automatically data
are distributed along of all shards.

11. Fragmentation

12. Fragmentation

13. Architecture
Shards Servers: mongod –shardsvr
You can configure replication to dealing with failures.
Shards Routers: mongos –configdb
urlconfig:portconfig
It is the shell for the rest of clients.
It can be executed in an application server for reduce
the load of the server.
Config Routers:mongod –configsvr
Recommended a group of 3

14. Logical architecture

15. Important note
_id
Special key
Present in all stored documents
Unique to each collection
It can be the type you want

16. First step with sharding
use admin
db.runCommand( { addshard : "pre­mongo1:10000" } );
db.runCommand( { addshard : "pre­mongo2:10000" } );
db.runCommand( { enablesharding : "activities" } );
db.runCommand( { shardcollection :
"activities.userWall" , key : { userId: 1 } } );
db.printShardingStatus()

17. Backup
EC2 → Snapshot EBS
LVM→ Snapshot LV
FS→mysqldump, dd (with sharding not recommended)
Weak point of sharding.
More details ­> http://bit.ly/wNdlIA

18. Questions?

19. Who am I?
Spanish web: http://www.juanvicenteherrera.es
English web: http://www.juanvicenteherrera.eu
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LinkedIn: http://es.linkedin.com/in/jvherrera