Book Image

Data Exploration and Preparation with BigQuery

By : Mike Kahn
Book Image

Data Exploration and Preparation with BigQuery

By: Mike Kahn

Overview of this book

Data professionals encounter a multitude of challenges such as handling large volumes of data, dealing with data silos, and the lack of appropriate tools. Datasets often arrive in different conditions and formats, demanding considerable time from analysts, engineers, and scientists to process and uncover insights. The complexity of the data life cycle often hinders teams and organizations from extracting the desired value from their data assets. Data Exploration and Preparation with BigQuery offers a holistic solution to these challenges. The book begins with the basics of BigQuery while covering the fundamentals of data exploration and preparation. It then progresses to demonstrate how to use BigQuery for these tasks and explores the array of big data tools at your disposal within the Google Cloud ecosystem. The book doesn’t merely offer theoretical insights; it’s a hands-on companion that walks you through properly structuring your tables for query efficiency and ensures adherence to data preparation best practices. You’ll also learn when to use Dataflow, BigQuery, and Dataprep for ETL and ELT workflows. The book will skillfully guide you through various case studies, demonstrating how BigQuery can be used to solve real-world data problems. By the end of this book, you’ll have mastered the use of SQL to explore and prepare datasets in BigQuery, unlocking deeper insights from data.
Table of Contents (21 chapters)
Free Chapter
1
Part 1: Introduction to BigQuery
4
Part 2: Data Exploration with BigQuery
10
Part 3: Data Preparation with BigQuery
14
Part 4: Hands-On and Conclusion

Understanding query structure

A BigQuery query is an SQL statement that is used to select, filter, and transform data stored in BigQuery tables. To effectively query data in BigQuery, it is essential to understand the structure of a query and the purpose of each element. A BigQuery query follows a specific syntax and consists of various clauses that work together to retrieve the desired information from your datasets. Let’s break down the sections of a SQL query in BigQuery in detail.

Action command – the SELECT clause

The commands that are used in the SELECT area of your query tell the analysis engine what needs to be done. SELECT extracts data from a table.

The SELECT clause chooses the columns you want to retrieve in the result. It determines what data you want from a table and defines calculations or transformations. You can specify columns to be returned by name or use the wildcard operator (*) to select all columns (note that it is not advised to use this...