I still remember that day. A day that shall live on in infamy in my mind. Well over a decade ago, in the days when SQL Server roamed the land devouring souls on the Altar of Stored Procedures. There was only one tool available at the time. SQL. That’s it. There was one problem that had to be solved.
The answer? A recursive CTE.
At the same time … both a demon of the dark and a shining angel from the heavens. Just depends on your view.
Photo by Michael Carruth on Unsplash
Anyone who’s been working in Data Land for any time at all, knows that the reality of life very rarely matches the glut of shiny snake oil we get sold on a daily basis. That’s just part of life. Every new tool, every single thingy-ma-bob we think is going to solve all our problems and send us happily into the state of nirvana inside our eternal data pipelines, is a lesson in disappointment.
I get it, there are a lot of nice tools out there. I use some of them every day. But, a healthy dose of reality is good for us all. Don’t lie to yourself. There is no such thing as the perfect tool. There are good tools, bad tools, and tools in between. The Truth is that all tools get pushed to their limits at some point.
We work on small teams, we don’t have all the time in the world, and we have to deliver our data at some point, perfect or not. We cut corners, hopefully, the right ones. That’s part of being wise and putting years of data experience to work. Today I’m going to talk about my experience of running Databricks + Delta Lake at scale. What happens when you use Databricks to ingest and deal with 10’s of millions of records a day, billions+ records a month?
Photo by Amador Loureiro on Unsplash
Hmm … data types. We all know they are important, but we don’t take them very seriously. I mean we know the difference between boolean, string, and integers, those are easy to get right. But we all get sloppy, sometimes we got the string and varchar route because we don’t spend enough time on the data model to care.
Can a string versus a int or bigint in Delta Lake with Spark have a big impact on performance? Data size? Does it matter? Let’s find out.
Anyone who’s been roaming around the forest of Data Engineering has probably run into many of the newish tools that have been growing rapidly around the concepts of Data Warehouses, Data Lakes, and Lake Houses … the merging of the old relational database functionality with TB and PB level cloud-based file storage systems. Tools like Delta Lake, lakeFS, Hudi, and the like.
Sure, these tools have been around for some time, but the uptake and adoption of them all have been rapidly growing. I use Delta Lake on a daily basis, taking advantage of the many wonderful features it provides to simplify and reduce complexity in data pipelines. But, I’ve been sitting around for a long time waiting for the plethora of “add-on” tooling to come out, stuff that will make my life easier. I recently saw one of the first tools like that for Delta Lake, namely mack.
Mack appears to have the ability to “do the hard work for you,” a concept that appears to be growing in popularity, but which I have a fraught relationship with. Double-edged sword? Let’s find out.
Nothing captures the imagination and heart like a tale of betrayal and heartbreak, and that is a tale I want to bring to you today. It’s a tale of Databricks Workflows and Jobs, version changes, new features, API’s, and insidious little hidden gems that will make you pull your hair out when you find them. It’s a tale of what not to do, a tale of how to put developer and customer experience first, instead of forcing unwanted solutions down the throats of the little birdies feeding at your nest.
As a Data Engineering simplicity and ease of use is something close to my heart, something that Databricks did well, or maybe I should say used to do well … before recent releases like Jobs 2.1 API. I hope you can hear the bitterness oozing from my words.
There are probably few things in life that will strike more fear and tumult in the heart of the Data Engineer than historical loads. You know, on the surface it seems like such an innocent thing. How could it possibly be, just take a bunch of data stored somewhere and shove it into a table. If only. Life never works that way, and neither does the historical load. You would think after decades we all would have figured it out you know. Is it because we don’t do it enough? Maybe it’s like regex, you just figure it out as you go every single time, telling yourself you’ll do it right next time.
An interesting topic of late that has been rattling around in my overcrowded head is the idea of Big Data vs Not Big Data, and the intersection thereof. I’ve been thinking about SAAS vendors, the Modern Data Stack, costs, and innovation. A great real-life example of all these topics is Delta Lake. Delta Lake is the child of Databricks, officially or not, and at a minimum has exploded in usage because of the increasing usage of Databricks and the popularity of Data Lakes.
Delta Lake, Hudi, Iceberg, all these ACID/CRUD abstractions on top of storage for Big Data have been game changers. But, as with any new popular tech, it comes with its own set of challenges. Specifically for Delta Lake … if you want to use it 99.9% of people are going to have to use Spark to do so, which can be costly, in terms of running clusters, and add complexity, in terms of new tooling, data pipelines, and the like. Anytime you only have one path to take with a tool, innovation is stifled, and barriers arise. Enter delta-rs the Standalone Rust API for Delta.
Do this, not that. Well, I’ve got my own list. With everyone jumping on the PySpark / Databricks / EMR / Glue / Whatever bandwagon I thought it was long overdue for a post on what to do, and not to do when working with Spark / PySpark. I take the pragmatic approach to working with Spark, it’s honestly very forgiving well and far into the 10s of TBs of data. Once you wander past that point things tend to get a little spicy if you don’t have it all dialed in. As with most things in life if you get a few things right, and of course don’t do some things, that will get you a long way, the same applies to Spark.
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So, you’ve heard about dbt have you. I honestly can’t decide if it’s here to stay or not, probably is, enough folks are using it, and preaching about it. I personally have always been a little skeptical of dbt, not because it can’t do what it says it can do, it can, but because I’m old and bitter from my many years of Data Engineering, and I always see the problems in things.
But, I will let you judge that for yourself. Today I want to give a brief overview of dbt, kick the tires, muse about its features, and most importantly, look at dbt from a Data Engineering perspective, ferret out the good, the bad, and the ugly. I will try my best to be nice but don’t count on it. Code is on GitHub.
Ever since playing with Great Expectations with Spark some time ago, I’ve been on the lookout for more Data Quality at-scale tools. The market still has a long way to go with these tools, not enough options, hard to use, and the typical Data Engineering travails. I came across soda-core recently, a self-proclaimed…
“Data reliability testing for SQL- and Spark- accesssible data.“
soda-core docs
Doing anything at scale, well … that’s usually the problem. Data Quality and Observability are topics were hear a lot about these days. The reality often doesn’t meet the expectations most of the time. Even Great Expectations, being awesome, can get complicated real quick-like. Let’s hope that soda-core pair with Spark can show us some real promise. Code available on GitHub.
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