3rd Party Platform Unique Identifier for Joins vs Internal Identifiers What is the general practice when it comes to choosing a unique identifier? In my case I have the option to use the eBay unique listing ID (Item ID) or my own internal ID for use in table joins and general identification. The argument could be made that some 3rd party identifiers are non-numeric and I would understand this proposition but in my specific case the identifier is numeric. Thanks for any advice or personal experiences in advance!
To be safe you'll want both. Internally you should create and use your own unique IDs to maintain a clean relational model with FKs between your tables while keeping a reference to the eBay unique ID in an appropriate table. If you need to reference something by the eBay ID you will have it available, but should the eBay unique ID rules change it does not affect the consistency of your existing table relations and architecture.