Grouping Sets

Learn and practice grouping sets in PostgreSQL.

We'll cover the following

The rollup clause
The cube clause
Try it yourself

There is a restriction that comes with using classic aggregates—we can only run them through a single group definition at a time. In some cases, we want to be able to compute aggregates for several groups in parallel. For those cases, SQL provides the grouping sets feature.

In the Formula One competition, points are given to drivers and then used to compute both the driver’s champion and the constructor’s champion points. Can we compute those two sums over the same points in a single query? Yes, of course, we can:

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Part I: Preface

Introduction to PostgreSQL

Part II: Introduction to Structured Query Language

Part III: Writing SQL Queries

Business Logic

A Small Application

The SQL REPL: An Interactive Setup

Indexing in PostgreSQL

Part IV: SQL Toolbox

SQL Tools

Managing Output in SQL

Understanding Nulls

Window Functions

Relations and Joins

Part V: Data Types

Serialization and Deserialization

PostgreSQL Data Types 101

Denormalized Data Types

Part VI: Data Modeling

Object Relational Mapping and Tooling for Database Modeling

Normalization

Practical Use Case: Geonames

Modelization Anti-Patterns

Denormalization

Not Only SQL

Part VII: Data Manipulation and Concurrency Control

Another Small Application

Isolation and Locking

Computing and Caching in SQL

Triggers

Listen and Notify

Batch Update, MoMA Collection

Part VIII: PostgreSQL Extensions

What’s a PostgreSQL Extension?

Auditing Changes with hstore

Million Song Dataset

Using Trigrams for Typos

Denormalizing Tags with intarray

The Most Popular Pub Names

Geolocation with PostgreSQL

Counting Distinct Users with HyperLogLog

Appendix

Grouping Sets