1. 1
1
Smit Shah
Yuliana Havryshchuk
Democratizing Data Quality
at Zillow through a
Centralized Platform

2. 2
Who We Are
Data Governance Platform Team
@ Zillow
Smit Shah
Senior Software Development
Engineer, Big Data
Yuliana Havryshchuk
Software Development Engineer,
Big Data

3. 3
Agenda
● What is Zillow?
● Data Quality Challenges
● Centralized Data Quality Platform
○ Architecture
○ Self-Service
○ Pipeline integration
● Key Takeaways

4. Zillow

5. About Zillow
● Reimagining real estate to make it
easier to unlock life’s next chapter
* As of Q4-2020
● Offer customers an on-demand
experience for selling, buying,
renting and financing with
transparency and nearly seamless
end-to-end service
● Most-visited real estate website in
the United States

6. Data Quality Challenges

7. Why Monitor Data Quality?
● Data fuels many customer facing
and internal services at Zillow that
rely on high quality data
○ Zestimate
○ Zillow Offers
○ Zillow Premier Agent
○ Econ and many more
● Reliable performance of ML and
Services requires certain level of
data quality

8. Challenges we Faced
● No standard way to monitor quality
● Lack of visibility into data health
● No known lineage between data and processes

9. Centralized Data Quality
Platform

10. Data
Quality
Platform
Increase Visibility of
Data Health
Integrate with Data
Lineage
Support Built-in
Alerting
Enable Safe
Evolution of Rules
Standardize Data
Quality Rules
5 Pillars for Data Quality Platform

11. Platform Architecture
* As of May 2021

12. Platform Architecture
* As of May 2021

13. Platform Architecture
* As of May 2021

14. Platform Architecture
* As of May 2021

15. Platform Architecture
* As of May 2021

16. Platform Architecture
* As of May 2021

17. Platform Architecture
* As of May 2021

18. Self-Service Capabilities

19. Self-Service Onboarding - Goals
● Must be scalable
● Must be accessible to all user archetypes
● Must require minimal configuration

20. Self-Service Onboarding - Data Discovery
* These values are simulated

21. Self-Service Onboarding - Example
* These values are simulated
id name type page_views data_date
1 123 Green St house 709 2021-05-01
2 47 Walker Rd townhouse 132 2021-05-01
1225 City St #901 condo 800 2021-05-01
4 47 Walker Ave test 600 2021-05-01

22. Self-Service Onboarding - Rule-based
* These values are simulated

23. Self-Service Monitoring - Rule-based
* These values are simulated

24. Self-Service Onboarding - Example
* These values are simulated
id name type page_views data_date
1 123 Green St house 709 2021-05-01
1 123 Green St house 820 2021-05-02
1 123 Green St house 12 2021-05-03
1 123 Green St house 760 2021-05-04

25. Self-Service Onboarding - Metrics
* These values are simulated

26. Overview Metric
* These values are simulated
Self-Service Onboarding - Monitoring

27. Behind the Scenes
● Rule-based monitors turn into contracts
● Metrics monitors turn into ML-based anomaly detection
● Register data quality requirements in config stores
● Dynamically generate validation pipelines

28. Validation Libraries
Built in-house:
● Luminaire Contract Evaluation Library (scala) for rule-based constraints
● Luminaire Anomaly Detection Library (python) for time-series metrics
○ https://github.com/zillow/luminaire

29. Pipeline Integration

30. Pipeline Integration (before)
Producers
Consumers

31. Pipeline Integration (after)
Producers
Consumers
*

32. Validation Results
● Alert data users if any checks fail
● Integrate with pipeline execution to prevent propagation
● Provide visibility through data discovery tool
● Provide common understanding between producers and consumers

33. Future Direction
● Tighter integration between components
● Expand libraries to support more use-cases
● Move from detection to diagnosis
● Validation for streaming data

34. Key Takeaways

35. Key Takeaways
● 5 pillars that helped us build a robust platform: standardization,
visibility, evolution, alerting, lineage
● Alerting on data quality issues early allows proactive response
● Producing quality data increases trust in data and improves decisions
made
● Data quality is a shared responsibility, and collaboration is needed to
be successful

36. Questions?
Thank you!
https://www.zillow.com/careers/