This, dear reader, is not so much a sermon as it is a bedtime story for architects and other brave wanderers of the Software Realm. A tale told in three wibbly-wobbly parts, full of whispers and warnings. It begins, as many fine stories do, in a curious land—a kingdom of Microservices, where APIs chatter like birds and Data dwells in a great central lake (which everyone agrees is quite deep, but no one dares measure).
Now in this peculiar place, the clever folk who lived there practiced the Noble Art of Decomposition. Every service had a single sacred purpose and kept its secrets hidden behind a finely carved interface. “Speak to me politely, and I shall tell you what you need,” said each module with a prim little bow. “But dare not peek into my private drawers.”
Ah, but they did peek. Of course they did.
Tale the First: Of the User Who Wouldn’t Be Shared
Once upon a sprint or two ago, there lived a UserModule, who was quite proud of her well-groomed tables. Along came the SalesModule, who said:
“I merely need a name! A name and perhaps a birthday! ‘Tis all!”
The SalesModule, too lazy (or perhaps too rushed) to ask politely through the UserModule’s formal API gate, tiptoed ‘round the back and peeked straight into the drawers.
“JOIN me,” whispered the query.
And thus, Sales and User were tangled together like a pair of enchanted socks—impossible to separate, and deeply unfortunate when one wished to change the pattern of the other.
When the UserModule wished to evolve—add new pockets, rearrange compartments—it found itself stuck. For if it moved even a single drawer, the SalesModule would shriek in horror and burst into SQL tears.
The elders proposed a dual-table dance: one for the new world, one for the old. The former twinkled with promise. The latter clung to life with the desperation of a deprecated dependency. “We’ll switch over soon,” they all swore.
They never did.
Tale the Second: Of the Workflow That Wandered
In a distant corner of the land, where events fluttered like butterflies and every task waited in a queue, there resided the noble WorkflowModule. This creature had an API so rich it was said one could sip tea and still finish a request before the scone cooled.
But lo! A lurking application, small and mostly forgotten, reached into Workflow’s drawers without so much as a knock. It JOINed where it should not JOIN.
Fortunately, this tale has a happier ending. The wayward application was taught better manners, sent to finishing school (via a Pull Request), and began to use the API like a proper citizen. WorkflowModule packed its bags, moved to a nicer database, and everyone clapped.
Tale the Third: Of the Mongo That Moved
And then—joy!—a tale of triumph!
There once was a Mongo database, large and bloated like an overfed walrus. It waddled under the weight of its own data. “Help me!” it cried.
And because none of the villagers had touched its inner workings directly—only spoke to it through its polite and predictable API—it was easy to help. A few structural adjustments, a brisk deployment, and voilà! The walrus danced.
Moral: Lock Your Drawers
If you are the keeper of data, guard it jealously! Lock it with keys known only to yourself. If another module wishes access, let it knock and request through your door, not sneak in through your plumbing.
Security can enforce this—only those with the right identity-token-spell may peer inside. Code reviews may spot intrusions, but only if all are vigilant. For the most stubborn intruders, you may offer a read-only looking-glass—something reflective and safe. But beware: not all dragons can be slain with views.
As for reporting? A perennial problem. Reporters want to see all, slice all, know all. You may need a replica palace just for them—a Reporting Database, where the public may roam freely among statues of yesterday’s schema.
So take heed, dear developer, for schema changes come as often as undergarment swaps (for some, at least). The more entangled your modules, the more dramatic the pantomime when change arrives.
Avoid the JOIN temptation.
Or be prepared to write fairy tales about the consequences.
This blog had some styling help from ChatGPT.