Introduction to

Time Series

🤩 Motivation

since v5 13th July 2021
improved in v6 19th July 2022
official docs had no small example
barely any blogs and videos

Christoph Ahlers

🎤 Presenter

Christoph Ahlers

Software Engineer / Consultant since 2018
at OpenValue since October 2021

Christoph Ahlers

🪜 Agenda

What is Time Series data?
Time Series in MongoDB
Live Demo with Spring
Tips and Pitfalls

Christoph Ahlers

What is Time Series data?

🤔

Christoph Ahlers

🤔 What is Time Series data?

Christoph Ahlers

finance

weather

IoT

Finance photo by Maxim Hopman on Unsplash

🤔 What is Time Series data?

🕝 timestamp
📏 measurement (one or more values)
🗺️ meta info (device, data type)

Christoph Ahlers

Time Series in

Christoph Ahlers

Time Series in

used like Collections
brings new special pipeline operations
Benefits vs Collections:
- reduced complexity for developers
- improved performance
  - improved query efficiency
  - reduced disk usage
  - reduced I/O for read operations
  - increased cache usage
  - 💰cheaper

Christoph Ahlers

Granularity

Data is always stored in Documents
granularity bundles values into single Document:

improves performance, reduces size
should match unique source's entry rate
⚠️ can only be raised!

Christoph Ahlers

granularity	bundled time span
seconds (dflt)	1 hour
minutes	24 hours
hours	30 days

🪣🪣 Buckets

🪣

average, min, max, first, last, count, ...

Christoph Ahlers

Live Demo with Spring

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📦 Dependencies

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>

<properties>
  <testcontainers.version>1.17.5</testcontainers.version>
</properties>
...
<dependency>
   <groupId>org.testcontainers</groupId>
   <artifactId>mongodb</artifactId>
   <version>${testcontainers.version}</version>
   <scope>test</scope>
</dependency>
<dependency>
   <groupId>org.testcontainers</groupId>
   <artifactId>junit-jupiter</artifactId>
   <version>${testcontainers.version}</version>
   <scope>test</scope>
</dependency>

Tests:

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Live Demo with Spring

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Tips & Pitfalls

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😇

😈

😇 Tips

use MongoDB Compass to test/explore/verify

Christoph Ahlers

😈 Pitfalls

Spring Data MongoDB is not feature complete
- expireAfterSeconds missing
- no check if Time Series collection
- Index creation via Spring Annotations (data.mongodb.auto-index-creation: true)
  creates Collection, not Time Series!
Index must use actual fields of metaField
metaData.deviceId

Christoph Ahlers

Conclusion

📚

Christoph Ahlers

📚 Conclusion

Granularity
integration in Spring
- Time Series definition
- Collection & Index creation via MongoTemplate
- MongoRepository
- Queries, Aggregations
  - $bucket
pitfalls and useful information