Validate Your Migrations!
Migrating data is never fun. It is, at best, a PITA, and at worst, a reason to go find a different job. But hey, sometimes you have no choice, and you just have to Go There, and that’s where Scientist comes in. Scientist ? Yeah, Scientist . But do wait, we’ll get to it in just a moment. First, let’s just look at what you’re probably going to be doing to migrate your data between, oh, whatever it is — databases, DB versions, applications, whatever. Basically, you’ll be doing some variation fo the Dual Write approach (•), which, roughly, translates to something like 1. Do all your Writes (Actually, Create / Update / Delete ) to both the Old , and the New targets, while serving Reads only from the Old target. 2. Start serving some of the Reads from the New target. 3. Eventually serve all the Reads from the New target. 4. Tu...