The document discusses the challenges faced by Shopify in using its existing data warehouse and ETL processes due to increasing data volume and complexity. It describes Shopify's attempts to use Pig and Luigi as well as Platfora to address these issues, but notes they did not meet Shopify's needs. Shopify then moved to using Spark due to its fast performance, nice development model using Python, and ability to better handle their data and query complexity. The summary provides an overview of why Shopify changed its data warehousing approach and the key technology it adopted.