Hacking MySQL’s JSON_ARRAYAGG Function to Create Dynamic, Multi-Value Dimensions

Making up for one of MySQL’s lesser-known shortcomings

Introduction

Let’s imagine that we’re members on the Data team at a subscription box company. In a MySQL database, transaction records of purchases are written to table named subscriptions. Metadata excluded, the table contains a customer_id and subscription field, and looks something like this:

Note that in this example scenario, a customer can have multiple subscriptions. The uniqueness of each …

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