Sponsored by Databricks. Databricks commissioned and funded this guide and reviewed it before publication for factual accuracy. They did not get to change the conclusions.
Full disclosure at the foot of this post.
Before I begin, let me tell you a true story. I was working with an online fashion retailer whose WooCommerce instance kept its own customer records, with a second Segment customer database behind it that everybody treated as the golden record.
Both systems gave every customer an ID. The two sets of IDs looked alike, and they were not the same thing.
The first time the