Databricks · Databricks Data Engineer Associate
Joins and unions
Databricks Data Engineer Associate · Lesson 9 of 22 · 59:40
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In this lesson
Prepare for the Databricks Certified Data Engineer Associate exam. In this lesson: inner and left joins, join keys and cross joins, broadcast joins, and unions (union, unionByName, UNION, and UNION ALL). Includes three original practice questions.
Preview the topics
- The joined table must keep every sale, even when its store ID is not yet in the stores table, and the store name can stay empty for those sales. Which join fits?
- A job joins two billion sales rows with the stores table, which holds three hundred rows, and the Spark UI shows a long shuffle of the sales. What should the data engineer change?
- The new stores send their sales with the same columns as the main sales table, in a different order, and after a union, prices show up in the store ID column. What should the data engineer use?