This document discusses Amazon DynamoDB's adaptive capacity capabilities. It describes how DynamoDB can automatically scale throughput and storage through dynamic partitioning to accommodate changing workloads. The new instant adaptive capacity feature allows partitions to instantly respond to traffic changes without lag. The document also compares provisioned and on-demand modes, noting that on-demand allows unlimited, pay-per-request scaling while provisioned requires capacity planning.

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Scale fearlessly with Amazon
DynamoDB adaptive capacity
Kai Zhao
Senior Product Manager
Amazon DynamoDB
A D B 3 0 2

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25x increase
Requestsperhour
900 writes/sec
25,000 writes/sec

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Objectives
Use DynamoDB more effectively
How DynamoDB scaling really works, from 1 RPS to millions of RPS
What’s new in adaptive capacity
When to use provisioned mode vs. on-demand mode

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Related sessions (online)
DAT201 – What’s New For Amazon DynamoDB
Tony Petrossian, Jeff Wierer
DAT321 – Amazon DynamoDB Under the Hood
Jaso Sorensen
DAT401 – Advanced Design Patterns for DynamoDB
Rick Houlihan

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Database capacity planning

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Vertical scaling

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Scaling NoSQL DBsHorizontal scaling

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The uneven access problem common to NoSQL
across data and time

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Just design for uniform access to your data, right?
Can be quite difficult in practice
Most NoSQL databases aren’t very forgiving
If your database isn’t flexible, you must handle more in your application
How does DynamoDB solve this for customers?

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DynamoDB adapts to your application, not vice versa

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Core functions of adaptive capacity
Dynamic partitioning Throughput governance

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Table1 Table2 Table3
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Behind the scenes…

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T1
Server 1
p.A
Storage scaling

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Server 1
T1
Server 2
A B
Storage scaling

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Server 1
T1
Server 2
A B
Storage scaling

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Server 1
T1
Server 2 Server 3
A B C
Storage scaling

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Server 1
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Server 2 Server 3
A B C
Storage scaling

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Server 1
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A D B C
Storage scaling

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Scenario: Census application
Statistics Canada (Canada's national statistical agency) hires you to build an online
census application.
You choose DynamoDB with the following key schema:
Partition key: province
Sort key: id

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What you didn’t realize…

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Server 1
Table
Server 2 Server 3 Server 4
Census traffic
64%
Ontario, Quebec, Newfoundland,
and Labrador Prince Edward
Island
British Columbia, Alberta,
Saskatchewan
Manitoba, Nova Scotia,
Northwest Territories
New Brunswick, Nunavut,
Yukon
28% 6% 2%

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Dynamic partitioning

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Dynamic partitioning

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Server 1 Server 2 Server 3 Server 4
Dynamic partitioning – behind the scenes
Ontario, Quebec, Newfoundland,
and Labrador Prince Edward
Island
British Columbia, Alberta,
Saskatchewan
Manitoba, Nova Scotia,
Northwest Territories
New Brunswick, Nunavut,
Yukon

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Server 2 Server 3 Server 4
Dynamic partitioning – behind the scenes
British Columbia, Alberta,
Saskatchewan
Manitoba, Nova Scotia,
Northwest Territories
New Brunswick, Nunavut,
Yukon
Server 1
Ontario
Server 5
Quebec, Newfoundland and
Labrador, Prince Edward Island

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Server 2 Server 3 Server 4
Dynamic partitioning – behind the scenes
British Columbia, Alberta,
Saskatchewan
Manitoba, Nova Scotia,
Northwest Territories
New Brunswick, Nunavut,
Yukon
Server 1
Ontario.A
Server 5
Quebec, Newfoundland and
Labrador, Prince Edward Island
Server 6
Ontario.B

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Server 7 Server 3 Server 4
Dynamic partitioning – behind the scenes
Alberta, Saskatchewan Manitoba, Nova Scotia,
Northwest Territories
New Brunswick, Nunavut,
Yukon
Server 1
Ontario.A
Server 5
Quebec, Newfoundland and
Labrador, Prince Edward Island
Server 6
Ontario.B
Server 2
British Columbia

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Summary of dynamic partitioning
DynamoDB adapts to your application, not vice versa
Automatic partitioning to equalize storage and throughput
Throughput-based partitioning currently available for on-demand mode

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Table
(items)
Per-item limits:
1,000 writes per sec
6,000 reads per sec (EC)

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DynamoDB Key Diagnostics Library
Graphs of frequently accessed
items
Lightweight wrapper around
DynamoDB SDK
AWS CloudFormation
template

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Server 1
T1
Server 4 Server 2 Server 3
A D B C
Adaptive capacity governance in 2018
A

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Server 1 Server 4 Server 2 Server 3
D B C
Adaptive capacity governance in 2018
AA
T1

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Adaptive capacity governance in 2018
Pros:
Accommodates imbalanced workloads
Helps you be more efficient (provision fewer WCUs and RCUs)
Cons:
Reactive process with 5–30 minute response

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New in 2019 – Instant adaptive capacity
No more response time
Partitions respond instantly in response to changing traffic

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Instant adaptive capacity – How it works

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Instant adaptive capacity – How it works

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Instant adaptive capacity – How it works

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Instant adaptive capacity – How it works

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Instant adaptive capacity
DynamoDB looks at what your table can do, not what partitions can do.
Key benefits:
• Instantly accommodates imbalanced workloads
• Sustains imbalanced workloads indefinitely
• Helps you reduce your DynamoDB bill
• On by default, no extra cost

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Get massive scalability and consistent performance
without worrying about partitions and uneven access
patterns

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DynamoDB on-demand
Features
• No capacity planning, provisioning, or
reservations—simply make API calls
• Pay only for the reads and writes you perform
Key benefits
• Eliminates tradeoffs of overprovisioning or
underprovisioning
• Instantly accommodates your workload as
traffic ramps up or down

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What are the maximum scaling
capabilities of on-demand mode?

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On-demand scaling properties
Minimum throughput
• Up to 4,000 write request units (WRU): 4,000 writes per second
• Up to 12,000 read request units (RRU): 24,000 EC reads per second
• Any linear combination of the two
Maximum throughput
• Unlimited!
Pay per request: use nothing, pay nothing

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DynamoDB request
rate
Maximum
throughput
“Up to twice your previous peak”

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“Up to twice your previous peak”

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Dynamic partitioning

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Instant high throughput

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Things to keep in mind
Initial doubling takes up to 30 minutes
Subsequent traffic scales instantly
Continuously monitored
• No need to achieve 2x previous peak to get more throughput
• Gracefully accommodates growth without throttling

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On-demand mode use case – Infrequent workloads

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Business impact

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When to use provisioned vs. on-demand
Use provisioned mode for:
• Steady workloads
• Gradual ramps
• Events with known traffic
• Ongoing monitoring
Use on-demand mode for:
• Unpredictable workloads
• Frequently idle workloads
• Events with unknown traffic
• “Set it and forget it”
Consider your tolerance for operational overhead
and overprovisioning

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DynamoDB adaptive capacity at a glance
Provisioned Mode On-demand mode
Governance Instant (provisioned capacity) Instant (account limits)
Default limits
(increasable)
40,000 WCU, 40,000 RCU 40,000 WRU, 40,000 RRU
Dynamic partitioning
(storage)
Automatic Automatic
Dynamic partitioning
(throughput)
Not available yet Automatic
Key Diagnostics Library Supported Supported

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Key takeaways
DynamoDB adapts to your application, not vice versa
Scale up or down at will, even with skewed data access patterrns
Focus on application traffic to your table and items, not on partitions
Provisioned mode for gradual ramps, on-demand mode for spikes

62. Thank you!
S U M M I T © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved.
Kai Zhao
kazh@amazon.com

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