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Great Expectations with Databricks and Apache Spark. A Tale of Data Quality.

Photo by Joshua Sortino on Unsplash

It still seems like the wild west of Data Quality these days. Tools like Apache Deque are just too much for most folks, and Data Quality is still new enough to the scene as a serious thought topic that most tools haven’t matured that much, and companies dropping money on some tool is still a little suspect. I’ve probably heard more about Great Expectations as a DQ tool than most.

With the popularity of PySpark as a Big Data tool, and Great Expectations coming into its own, I’ve been meaning to dive into what it would actually look like to to use Great Expectations at scale and answer some simple questions. How easy is it to get up and running with Spark, what’s the path of least resistance to getting some basic Data Quality checks in place in a data pipeline.

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Reducing Complexity with Databricks + Delta Lake COPY INTO

As the years drag by in Data Engineering, there are a few things that I have come to appreciate more and more. One of those topics that is close to number one on the list is complexity reduction. Today’s modern data stacks are filled to the brim with technologies and tools, full to the brim, and overflowing. So many tools with such wonderful features, sometimes all the magic comes with a downside. Complexity. Complexity can turn something wonderful into a nightmare.

Reducing (not avoiding) complexity seems to be one of the main tenets I work on these days when designing resilient, reliable, and repeatable data pipelines that can process terabytes of data. One of those tools is COPY INTO feature of Databricks + Delta Lake.

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Data Quality – Great Expectations for Data Engineers

Mmmm … Data Quality … it is a thing these days. I look forlornly back to the ancient days of SQL Server when nobody cared about such things. Alas, we live in a different world, where hundreds of terabytes of data are the norm, and Data Quality becomes a thing. I’ve been meaning to give Great Expectations a poke for like a year, but just haven’t had the time or inclination to do so, but times are changing, and so should I.

I’m not really planning on giving an in-depth guide to Data Quality with Great Expectations, what I’m more interested in are topics like, how easy is it to set up and use, what’s the overhead, what are the main features and concepts and are they easy to understand. I find this sort of review of Data Engineering tools to be more helpful than simply a regurgitation of the documentation.

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Part 4 – Keys To Success – Idempotency and Partitioning.

As the road winds on we come to Part 4, of our 5 Part Series on Data Warehouses, Lakes, and Lake Houses. Finally, we are getting to some fun topics after all the boring stuff. Today I want to talk about the two keys to success in your Data Lakes … Idempotency and Partitioning. I firmly believe these two concepts are the cornerstones of the new exciting, or not-so-exciting world of Data Lakes and Lake Houses, without which your data and pipelines go the way of the dodo.

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Databricks + Delta Lake MERGE duplicates – Deterministic vs Non-Deterministic ETL.

Is there any problem more classic to the Data Lakes and Data Warehouses than duplicate records? You would think after doing the same ETL for over a decade I could avoid the issue, apparently not. It’s good never to think too highly of one’s self, the duplicates can get us all. Today I want to talk about a wonderful feature of Databricks + Delta Lake MERGE statements that are perfect for quietly and insidiously injecting duplicates into your Data Warehouse or Data Lake. This is a great trick to play on your unsuspecting coworkers.

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End-to-End Pipeline Integration Testing for Databricks + Delta Lake.

The testing never ends. Tests tests tests, and more tests. When it comes to data engineering and data pipelines it seems good practices are finally catching up after years. In the past, the data engineering community took a lot of heat, and rightly so, for not adopting good software engineering principles, especially in data pipelines.

In the defense of many data engineers, because of the varied backgrounds people come from, some were never taught or realized the importance of good software design and testing practices. Sure, it always “takes more time” upfront to design data pipelines with code that is functional and unit-testable, and worse, able to be integration tested from end to end. It requires some foresight and thought in both data architecture and pipeline design to enable complete testability.

Integration testing end-to-end in an automated manner is a tough nut to crack. How can you do such a thing on massive pipelines that crunch hundreds of TBs of data? With a little creativity.

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Part 3 – Data Modeling in Data Warehouses, Data Lakes, and Lake Houses.

Now we are getting to the crux of the matter. I would say Data Modeling is probably one of the most unaddressed, yet important parts of Data Warehousing, Data Lakes, and Lake Houses. It raises the most questions and concerns and is responsible for the rise and fall of many Data Engineers.

This is what really drives the difference between the”big three”, Data Modeling.

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Part 2 – How Technology Platforms affect your Data Warehouse, Data Lake, and Lake Houses.

This is a start of a 5 part series on Demystifying Data Warehouses / Data Lakes / Lake Houses. In Part 2 We are digging into the common Big Data tools and how those technologies have a direct impact on Data Models and what kind of Datastore ends up being designed.

Part 1 – What are Data Warehouses, Data Lakes, and Lake Houses?

Part 2 – How Technology Platforms affect your Data Warehouse, Data Lake, and Lake Houses.

Part 3 – Data Modeling in Data Warehouses, Data Lakes, and Lake Houses.

Part 4 – Keys To Sucess – Idemptoency and Partitioning.

Part 5 – Serving Data from your Data Warehouse, Data Lake, or Lake House.

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5 Part Series – Demystifying Data Warehouses / Data Lakes / Lake Houses

Even I get confused these days. Data Warehouse, Data Lake, and Lake Houses … why do we have three, what are the differences? Is it all just marketing huff-a-luff? Technology and life in the data world seem to be changing fast these days. Lot’s of new vendors on the streets trying to hawk their tools and solutions, each of them pumping out content designed to solve all your data needs.

I’ve seen a lot of content out there by SAAS vendors, and by folks who ascribe to a said vendor, about Data Lakes and Lake Houses, new schema designs and approaches, and it’s hard to know what is just a sales tactic and what is real. I’m going to stir the pot.

This is a start of a 5 part series on Demystifying Data Warehouses / Data Lakes / Lake Houses. Enjoy.

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Hive Metastore in Databricks – What To Know.

Hive is like the zombie apocalypse of the Big Data world, it can’t be killed, it keeps coming back. More specifically the lesser-known Hive Metastore is the little sneaker that has wormed its way into a lot of Big Data tooling and platforms, in a quasi behind the scenes way. Many people don’t realize it, but Hive Metastore is the beating heart behind many systems, including Databricks. It’s one of those topics that sneaks up on you, ignore it happily at your own peril, till all of a sudden you need to know everything about it.

Specifically, I want to talk about Hive MetaStore as related to Databricks, how it works inside the Databricks platform, and what you need to know. I tripped myself up a lot during my initial forays into Databricks at a Production level. When you wander outside the realm of Notebooks, which you should, strange things start to happen. Databricks seems to assume you already have your own Hive Metastore, maybe like the Glue Data Catalog, or that you want to set up your own somewhere. But what if you don’t?

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