Using Delta lake merge to update columns and perform upserts
This blog posts explains how to update a table column and perform upserts with the merge command. We explain how to use the merge command and what the command does […]
Vacuuming Delta Lakes
Delta lakes are versioned so you can easily revert to old versions of the data. In some instances, Delta lake needs to store multiple versions of the data to enable […]
Compacting Small Files in Delta Lakes
This post explains how to compact small files in Delta lakes with Spark. Data lakes can accumulate a lot of small files, especially when they’re incrementally updated. Small files cause […]
Compacting Parquet Files
This post describes how to programatically compact Parquet files in a folder. Incremental updates frequently result in lots of small files that can be slow to read. It’s best to […]
Broadcasting Maps in Spark
Spark makes it easy to broadcast maps and perform hash lookups in a cluster computing environment. This post explains how to broadcast maps and how to use these broadcasted variables […]
Reverse Engineering Spark Structured Streaming and Trigger.Once
Spark Structured Streaming and Trigger.Once make it easy to run incremental updates. Spark uses a checkpoint directory to identify the data that’s already been processed and only analyzes the new […]
Introduction to Delta Lake and Time Travel
Delta Lake is a wonderful technology that adds powerful features to Parquet data lakes. This blog post demonstrates how to create and incrementally update Delta lakes. We will learn how […]
Fast Filtering with Spark PartitionFilters and PushedFilters
Spark can use the disk partitioning of files to greatly speed up certain filtering operations. This post explains the difference between memory and disk partitioning, describes how to analyze physical […]
How to use the Spark Shell (REPL)
The Spark console is a great way to run Spark code on your local machine. You can easily create a DataFrame and play around with code in the Spark console […]
Managing the SparkSession, The DataFrame Entry Point
The SparkSession is used to create and read DataFrames. It’s used whenever you create a DataFrame in your test suite or whenever you read a Parquet / CSV data lake […]