Idempotent database inserts: Getting it right
Idempotence is a critical concept in software systems, ensuring that a given operation can be performed multiple times without changing the system's state beyond the initial application. It's particularly important in database operations, where duplicate inserts can wreak havoc on data integrity and lead to subtle, hard-to-debug errors. When done right, idempotent inserts enable fault tolerance and consistency in the face of retries, failures, and distributed system complexities.
We create a table and attach a unique non-nullable column idempotency_key, when writing the record to the table we check if the operation is colliding on the unique constraint of the idempotency_key and in that case do nothing.
With this implementation, we increased the resilience of the system by allowing it to retry a given action. But let's look a bit deeper into edge cases and the behavior of the proposed solution.
The outcome of the two statements would be: Only the first insert statement would be saved in the database and the second insert will execute successfully but will not write a second row.
