engineering
Every API that accepts non-idempotent operations eventually has the duplicate-charge incident. A customer's mobile client retries a payment because the request appeared to hang. The original request actually succeeded but the response was lost on the way back. The retry succeeds too. The customer is charged twice. The
history
The schoolroom version of the stirrup goes like this. Charles Martel adopted the stirrup, defeated the Umayyads at Tours in 732, and the resulting need for heavily armored mounted warriors created the manorial system that became European feudalism. This compact narrative is from Lynn White's 1962 Medieval Technology
history
The wheel is the most-cited example of a primitive technology, but the engineering reality is the opposite. The wheel is a sophisticated solution that arrived late in human history, required several enabling technologies, and was independently invented far fewer times than most people assume.
engineering
The check-then-insert race condition is one of the oldest bugs in database programming. Postgres INSERT ON CONFLICT and the SQL standard MERGE give you atomic alternatives, but each has sharp corners that bite teams who reach for them without understanding the semantics.
engineering
Cache invalidation is famous as one of the two hard problems in computer science. Most of the difficulty is downstream of an earlier choice the team did not realize it was making: how the cache keys are structured. Get key design right, and invalidation becomes a one-line operation.
engineering
PgBouncer sits between your application and Postgres, multiplexing many client connections onto a small number of database connections. The pool mode you choose determines which Postgres features still work and which silently break.
engineering
Bulk import is the endpoint that wins or loses migration deals. A customer evaluating your API has a CSV from their old vendor and wants to know how painful it is to get into your system. The shape of the import endpoint determines the answer.
history
From Hellenistic grain mills to the Industrial Revolution, the watermill was the largest non-animal source of mechanical power in human civilization for two millennia. Most of what it accomplished is now forgotten because steam replaced it so completely.
history
The shipping container is one of the great unloved technologies. It does nothing clever, contains no surprising chemistry, and looks the same as it did in 1956. It also remade the global economy more thoroughly than the internet has, and almost nobody can name its inventor.
engineering
Postgres ships with a small kernel and an extension system that lets you bolt on functionality without forking the database. Most extensions are not worth the operational cost. A few earn their keep across nearly every production deployment.
engineering
Audit logs are the kind of feature that is trivial to add badly and surprisingly hard to add well. The wrong shape produces logs that are unsearchable, untrustworthy, expensive to store, and useless when someone actually asks what happened.
engineering
Adding a column with a default value to a 50-million-row table the naive way will lock production for the duration of the rewrite. The patterns that work avoid the rewrite, do the backfill in chunks outside transactions, and treat the migration as several deploys instead of one.