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Dask vs PySpark – Performance and Other Thoughts.

Every once in awhile I see someone talking about their wonder distributed cluster of Dask machines, and my curiosity gets aroused. I know plenty of people use Dask, mostly on their local machines, but it seems like the meteoric rise of Spark, especially with tools like EMR and Databricks, that Dask is slowly slipping into the shadows. I’ve had bad experiences with Dask in the past, trying to get it work well in production. I suppose that comes from working with tried and true Spark and other bullet proof distributed system. I’ve been meaning to return to Dask for awhile, compare a similar Dask and Spark cluster on performance … and other things like ease of setup and writing code. Let’s get too it.

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“Don’t mess with the dials,” they said. Spark (PySpark) Shuffle Partition Configuration and Performance.

Sometimes I amaze myself. I’ve been using PySpark for a few years now, happily crunching hundreds of TBs of data without much problem. Sure you randomly run into OOM errors and other such nonsense. Usually inspecting the code for something silly, throwing in a persist() or cache() here and there will solve 99% of the problems. I’ve always approached Spark performance with an overly pragmatic approach. Spark being the beast that it is, it’s easy to hide performance problems with more resources etc. I’ve generally tried to stay away from UDF's just using good coding practices and out of the box functionality. Ensuring good predicate pushdown’s, data partitioning etc are all helpful and important. But in the end… I don’t really know much about the out-of-the-box Spark configurations and how they affect performance.

Do the configurations change based on data size and partitioning strategy plus resources and cluster size? Probably. Does that seem complicated to figure out? Yes. Is the internet full of conflicting, vague and confusing advice? Of course.

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String Slicing Performance – Python vs Scala vs Spark.

Good ole’ string slicing. That’s one thing that never changes in Data Engineering, working with strings. You would think we would all get to row up some day and do the complicated stuff, but apparently you can’t outrun your past. I blame this mostly on the data and old schools companies. Plain text and flat files are still incredibly popular and common for storing and exporting data between systems. Hence string work comes upon us all like some terrible overload. The one you should fear the most is fixed width delimited files. I ran into a problem recently where PySpark was surprisingly terrible at processing fixed with delimited files and “string slicing.” It got me wondering … is it me or you?

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Python vs Scala – Concurrency.

One of the reoccurring complaints you always see being parroted by the smarter-then-anyone-else-on-the-internet Reddit lurkers is the slowness of Python. I mean I understand the complaint …. but I don’t understand the complaint. Python is what is is, and usually is the best at what it is, hence its ubiquitous nature. I’ve been dabbling with Scala for awhile, much to my chagrin, and have been wondering about its approach to concurrency for awhile now. I’ve used MultiProcessing and MultiThreading in Python to super charge a lot of tasks over the years, I want to see how easy or complex this would be in Scala, although I don’t think easy and Scala belong in the same sentence.

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Apache Airflow Integration with DataBricks.

The two coolest kids in class … I mean seriously … every other post in Data Engineering world these days is about Apache Airflow or DataBricks. It’s hard to kick against the goad. Just jump on the band wagon before you get left in the dust. I’ve used both DataBricks and Apache Airflow, they both are pretty important and integral tools for data engineers these days. Apache Airflow makes overall complex pipeline dependencies, orchestration, and management intuitive and easy. DataBricks has delivered with AWS and EMR could not, easy to use Spark and DeltaLake functionality without the management and config nightmares of running Spark yourself.

Recently I worked on an Airflow and DataBricks/DeltaLake integration, time to talk what it looks like and options when doing this type integration.

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Why Data Engineer’s should use AWS Lambda Functions.

When I used to think of lambda functions on AWS my eyes would glaze over, I would roll my eyes and say, “I work with big data, what in the world can a silly little AWS lambda function offer me?” I’ve had to eat my own words, those little suckers come in handy in my day to day engineering work. I want to talk about how every data engineer working with AWS can take advantage of lambda’s and add them to their data pipeline tool belt.

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Airflow vs Dagster

Dagster, the first few times I read the name, I just couldn’t take the tech stack seriously …. it’s still kinda hard. Today I want to compare Airflow vs Dagster, mostly explore what Dagster is and does. But I want to compare it to the popular Apache Airflow project so people have some context for it. It’s kinda hard keeping up on all the new stuff these days, I usually just wait till I see enough articles and tweet floating around about it, then I know it’s maybe worth a peak. Let’s crack open Dagster, and see if it’s better then the name chosen for it.

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Introduction to Apache Flink for Data Engineers

Not going to lie. I’ve been trying to figure out for awhile where Apache Flink fits in the Data Engineering world for awhile now. A year or two ago I didn’t seem much content posted about it, but it seems to be picking up stream. I’ve mostly managed to avoid understanding what Flink is or does, but I figured it’s time to give my brain a much needed workout. When I was ignoring Flink, I just chalked it up as another messaging/streaming system like Kafka or Pulsar. Apparently I was wrong … no surprise there.

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Introduction to Unit Testing with PySpark.

There are few things in life that are worse then cracking open some serious PySpark pipeline code, and then realizing there isn’t a single function written to encapsulate logic … wondering if some change you are about to make will bring down the whole pipeline. When you are new to a codebase you don’t know what you don’t know, you don’t have any backstory and you are usually flying by the seat of your pants in the beginning. When you have no unit tests, usually the only other way to test changes on a Spark pipeline are to run it …. which is sometimes easier said then done in a development environment. The first line of defence should be unit testing the entire PySpark pipeline.

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Introduction to Delta Lake on Apache Spark … for Data Engineers

If you’re anything like me when someone says Delta Lake you think DataBricks. But, the mythical Delta Lake is an open source project, available to anyone running Apache Spark. It seems also too good to be true, ACID transactions on the Spark scale? Incredible. This is the future, it has to be. The lines of what is a data warehouse have been starting to blur for a long time, I have a feeling Delta Lake will be the death blow to the traditional DW … or its rebirth??

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