This presentation will discuss scalability best practices with MongoDB. We will review how the following affect scalability: schema design, locking granularity within versions and engines, scaling vertically or horizontally, and collection sharding. Understanding how these topics can affect your application will help you avoid complications as your data and workload grows.

1. MongoDB Scalability Best
Practices
Jason Terpko
DBA, Rackspace/ObjectRocket
www.linkedin.com/in/jterpko
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2. Background
• Started out in relational databases in public
education then financial services
• Next came online media distribution
• For analytics, started working with columnar
databases and engines with compression
• First NoSQL project was application regression
testing
• Made the switch to NoSQL at ObjectRocket by
Rackspace
www.objectrocket.com
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3. Overview
• General Scalability
• Schema Design
• Scaling Options in MongoDB
• Locking
• Sharding
• Right Tool For the Job
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4. General Scalability
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Vertical (Up) Horizontal (Out)
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5. Schema Design
• Field Types
• Field Names
• Arrays
• Embedded Documents
• Document Size
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6. Documents
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{
"_id" : ObjectId("570680d891442f6efaff2005"),
"name" : "John Doe",
"age" : 45,
"height" : 5.9,
"weight" : NumberLong(165),
"updated_at" : "2016-01-07 15:46:32",
"active" : true,
"nickname" : null,
"zipcodes" : [ "10013" ],
"phone" : "212-555-1212"
}
{
"_id" : ObjectId("570680d891442f6efaff2005"),
"n" : "John Doe",
"a" : 45,
"h" : 5.9,
"w" : NumberLong(165),
"u" : ISODate("2016-01-07T15:46:32.085Z"),
"ac" : true,
"nn" : null,
"z" : [ "10013" ],
"p" : "212-555-1212"
}
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7. Scaling Options
In MongoDB • Vertical
• Replica Set
• Sharding (Horizontal)
• Pluggable Engine
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8. Vertical
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Client
• Hardware / Topology
• Reduced Complexity
• Increased Hardware Cost
• Upgrade Cycles
• Application Use Cases
• Requires Read Consistency
• Not Able To Shard
• Sharding Not Required
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9. Replica Set
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Client
• Hardware / Topology
• Reduced Complexity
• Reduced Hardware Cost
• Application Use Cases
• Allows For Eventual Consistency
• Not Able To Shard
• Sharding Not Required
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10. Sharding
www.objectrocket.com
MongoS
• Hardware / Topology
• Increased Complexity
• Better Utilization
• Application
• Written For Sharding
• Optional Eventual Consistency
• Increased throughput
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11. Pluggable Engine API
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MMAP

12. Locking
• MongoDB Version
• Database And Collections
• Engine
• Sharding
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13. Locking
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• MongoDB Defaults
• 2.4 & 2.6 – Database
• 3.0 – Collection
• 3.2 – Document
• Database and Collection Drops
• Database – Not free but cheap
• Collection - Free
• Engine
• MMAP – Database
• MMAPv1 – Collection
• WiredTiger – Document
• Rocks – Document
• TTL and Secondary's
• Added TTL Deletes
• Replication Batching
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14. Sharding
• MongoS
• Shard Key Selection
• Distributed Writes
• Targeted Operations
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15. MongoS
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Application
Application
Load Balancer
Application
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16. Shard Key Selection
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• Limitations
• Operations
• Unique Constraints
• Immutable
• Process
• Variety (Schema Analyzer)
• system.profile
• Staging and QA
• Chunks
• Preventing Jumbos
• Balancing Overhead
• Pre-splitting Collections
• Throughput
• Distributed Writes
• Targeted Ops
• Merging of Data
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17. Non-Distributed Writes
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10% 20% 30% 40%
Not an efficient use of all resources.
moveChunk()Key: {u: 1}
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18. Distributed Writes
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25% 25% 25% 25%
Efficient use of all resources
and write scopes.
Key: {u: “hashed“}
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19. Targeted Operations
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Efficient use of resources.
> db.mycoll.find({u: "...", c_at: "..." })
Key: {u: 1, c_at: 1}
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20. Partially Targeted
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Efficient use of resources.
Key: {u: 1, c_at: 1}
> db.mycoll.find({u: "...", u_at: "..." })
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21. Scatter-Gathers
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Not an efficient use of resources.
Key: {u: 1, c_at: 1}
> db.mycoll.find({u_at: "..." })
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22. Using the Right Tool :
Mongo
• Unstructured Data
• Retail Catalog Data
• Social Media User Data
• Analytic Data Rollups
• Gaming Profiles
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23. Using the Right Tool :
... maybe not Mongo
• Text Search
• Geo
• Key / Value
• Transactions
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24. Questions?
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Media Resources:
MongoDB Leaf - http://bit.ly/29bbJIR
RocksDB Logo - http://bit.ly/29cYFUS
WT Logo - http://bit.ly/294QEhw

25. Thank you!
Address:
401 Congress Ave Suite 1950
Austin, TX 78701
Support:
1-800-961-4454
Sales:
1-888-440-3242
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