Maintaining Your Data Lake At Scale With Spark


June 16th, 2019

50 mins 50 secs

Your Host

About this Episode


Building and maintaining a data lake is a choose your own adventure of tools, services, and evolving best practices. The flexibility and freedom that data lakes provide allows for generating significant value, but it can also lead to anti-patterns and inconsistent quality in your analytics. Delta Lake is an open source, opinionated framework built on top of Spark for interacting with and maintaining data lake platforms that incorporates the lessons learned at DataBricks from countless customer use cases. In this episode Michael Armbrust, the lead architect of Delta Lake, explains how the project is designed, how you can use it for building a maintainable data lake, and some useful patterns for progressively refining the data in your lake. This conversation was useful for getting a better idea of the challenges that exist in large scale data analytics, and the current state of the tradeoffs between data lakes and data warehouses in the cloud.


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  • Your host is Tobias Macey and today I’m interviewing Michael Armbrust about Delta Lake, an open source storage layer that brings ACID transactions to Apache Spark and big data workloads.


  • Introduction
  • How did you get involved in the area of data management?
  • Can you start by explaining what Delta Lake is and the motivation for creating it?
  • What are some of the common antipatterns in data lake implementations and how does Delta Lake address them?
    • What are the benefits of a data lake over a data warehouse?
      • How has that equation changed in recent years with the availability of modern cloud data warehouses?
  • How is Delta lake implemented and how has the design evolved since you first began working on it?
    • What assumptions did you have going into the project and how have they been challenged as it has gained users?
  • One of the compelling features is the option for enforcing data quality constraints. Can you talk through how those are defined and tested?
    • In your experience, how do you manage schema evolution when working with large volumes of data? (e.g. rewriting all of the old files, or just eliding the missing columns/populating default values, etc.)
  • Can you talk through how Delta Lake manages transactionality and data ownership? (e.g. what if you have other services interacting with the data store)
    • Are there limits in terms of the volume of data that can be managed within a single transaction?
  • How does unifying the interface for Spark to interact with batch and streaming data sets simplify the workflow for an end user?
    • The Lambda architecture was popular in the early days of Hadoop but seems to have fallen out of favor. How does this unified interface resolve the shortcomings and complexities of that approach?
  • What have been the most difficult/complex/challenging aspects of building Delta Lake?
  • How is the data versioning in Delta Lake implemented?
    • By keeping a copy of all iterations of a data set there is the opportunity for a great deal of additional cost. What are some options for mitigating that impact, either in Delta Lake itself or as a separate mechanism or process?
  • What are the reasons for standardizing on Parquet as the storage format?
    • What are some of the cases where that has led to greater complications?
  • In addition to the transactionality and data validation that Delta Lake provides, can you also explain how indexing is implemented and highlight the challenges of keeping them up to date?
  • When is Delta Lake the wrong choice?
    • What problems did you consciously decide not to address?
  • What is in store for the future of Delta Lake?

Contact Info

Parting Question

  • From your perspective, what is the biggest gap in the tooling or technology for data management today?


The intro and outro music is from The Hug by The Freak Fandango Orchestra / CC BY-SA

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