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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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Databricks Access Control – The 3 Most Important Steps

It’s not often I yearn for the good old days of SQL Server, but I’ve had a few of those moments lately. Some things I miss, some I don’t, and it’s probably because I’m getting old and crusty, stuck in my ways, by permissioning is one of those topics where I think about the good old days. Data access control and permissions are topics that we all kinda ignore as not that important … until we actually are trying to do something with them. Then all of sudden we start complaining about complexity and why this isn’t easier. That’s a good way to describe my reaction to having to work on Databricks Access control.

But, I learned a few things and I think they will be helpful for someone. Read on for the basics of handling permissions and access control in Databricks and Delta Lake.

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boto3 or aws cli for s3 … Python vs Bash and other thoughts.

For any Data Engineer working on aws for any length of time, there is one task that always seems to come up and never go away. Manipulating files on s3 a bucket on aws is something I’ve had to do for years, it just never goes away. It’s always something … listing files, moving files, copying files, checking for files, getting the last modified file, checking file sizes, downloading files … it pretty much never ends.

Luckily aws provides a few tools to make these easy, their handy cli for command-line work, or the trusty boto3 Python package. I want to give an introduction to the common commands Data Engineers have to run with both the aws cli and boto3 to perform various common tasks. We will then compare and contrast which tool to use in our pipelines and the pros and cons of each.

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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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Performance Testing Postgres Inserts with Python

Sometimes I get to feeling nostalgic for the good ol’ days. What days am I talking about? My Data Engineering days when all I had to worry about was reading files with Python and throwing stuff into Postgres or some other database. The good ol’ days. The other day I was reminiscing about what I worked on a lot during the beginning of my data career. Relational databases plus Python was pretty much the name of the game.

One of the struggles I always had was how fast can I load this data into Postgres? psycopg2 was always my Python package of choice for working with Postgres, it’s a wonderful library. Today I want to give a shout-out to my old self by performance testing Python inserts into Postgres. There are about a million ways and sizes and shapes to getting a bunch of records from some CSV file, through Python, and into Postgres.

I also enjoy making people mad … there’s always that. Nothing makes people mad at you like a good ol’ performance test 🙂

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ORM’s are the Cigarettes of the Data Engineering World.

Seriously, just don’t do it, they are bad for you. Listen to your mother, just say no. The dreaded ORM’s ( Object Relational Mapping ) that do all the hard SQL work for you. But, they come with many unintended consequences that are bad for your health and wellness in the long term. Many unsuspecting victims have been sucked into ORMs with the promise of an easier transition to allow programmers a familiar object-oriented design pattern for manipulating the data in a relational database, say Postgres or MySQL.

Again I tell you, don’t fall for the siren songs, there are tears and sorrow down the long and lonely ORM road.

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3 Tips for Unit Testing PySpark Pipelines

I’m not sure what it is, but some prevailing evil in the Data Engineering world has made it not so common for PySpark pipelines to be unit tested. Who knows, it’s probably a combination of things. Data Engineers have been accused of not having good Software Engineering principles. Functional testing is a hot commodity in the Software Engineering world but probably takes a while to trickle its way into mainstream Data Engineering. It can require good Docker skills. Also, generally speaking, the old school Data and ETL Developers that preceded Data Engineers in the bygone days never unit tested …. so neither do their ancestors.

Who knows? All that being said I want to give you 3 tips to help you unit test your PySpark ETL data pipelines.

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Review of Airbyte for Data Engineers

It’s hard to keep up with the never-ending stream of new Data Engineering tools these days. Always something new around the next bend. I find it interesting to kick the tries on the new kids on the block. It’s always interesting to see what angle or pain point a new tool tries to hone in on. I mean if you think about Data Engineering in general, the fundamentals really haven’t changed that much over the years, the tools change, but what we do hasn’t. We are expected to move data from point A to point B in a reliable, scalable, and efficient manner.

Today I’m going to be reviewing a tool called Airbyte. When I review a new product I’m usually incredibly basic about what I look for and I try to answer some easy and obvious questions. How easy is it to set up and use? What does the documentation look like? When I run into a problem can I solve it? Is the overhead of adding this new tool to a tech stack worth what features it offers? This is how we will explore Airbyte.

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Bitwise Operations for Data Engineers

Ugh. Cursed bitwise operations … something usually reserved for the low-level mythical engineers writing code no one should have to write. I’ve escaped all but twice during my meager existence, recently I had to use a bitwise operation while converting a Python hashing algorithm into PySpark code. It made my brain hurt. What is this wizardry all about anyways? It got me thinking, I should really attempt to learn something about bitwise operations since it comes up once every 10 years.

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gRPC for Data Engineers

If you’ve been around Data Engineering for a while, like me, you’ve noticed a few trends in the industry at wide, and in individual data engineers themselves. There seem to be a few types of data engineers, and it depends on where you’ve worked, and what your projects have looked like that put you here or there. Some data engineers focus on general ETL, Data Warehousing, and such things. They move data around and transform it using a myriad of tools. The other set of data engineers are more focused on infrastructure at a low level, they provide the underlying tools and services others use to make that data move around and transfer.

Which are you? One of those topics you may or may not be familiar with depending on your background is RPC or more specifically gRPC. What is it?

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