biology
When a caterpillar becomes a butterfly, most of its body is dissolved and reassembled. The schoolroom version of this transformation treats the caterpillar brain as deleted along with the rest. The actual biology is stranger: some memories survive.
api-design
CORS is the browser policy that controls which origins can call your API from JavaScript. Get it wrong in the permissive direction and you create CSRF vulnerabilities; get it wrong in the restrictive direction and customers cannot integrate from browsers at all.
history
The first human flight happened in November 1783, more than a century before powered aircraft. The Montgolfier brothers used paper, linen, and a smoky fire of straw and wool. The wrong theory of why it worked persisted for decades and led to several deaths.
postgres
Every index you add costs write throughput. pg_stat_user_indexes is the view that tells you which of those costs you are paying without getting any read-side benefit. Most production databases have several indexes that have not been read in months.
history
For 2000 years, the Aristotelian doctrine that nature abhors a vacuum blocked the conceptual leap that the atmosphere has weight. Torricelli's 1643 mercury tube was a thought experiment as much as a device: a column 76 cm tall that balanced against an invisible ocean of air.
biology
Horseshoe crab blood is blue, contains no white cells, and detects bacterial contamination at parts-per-trillion sensitivity. For 50 years, every injected medicine and implanted device has been tested with Limulus amebocyte lysate. The synthetic replacement has taken three decades to reach the
api
File uploads look simple until production traffic arrives. The naive single-POST design fails on large files, on unreliable mobile networks, on duplicate uploads, on partial failures. The patterns that scale handle resumability, deduplication, validation, and bounded storage cost.
postgres
pg_dump backs up one database. pg_dumpall backs up the whole cluster: every database plus roles, tablespaces, and cluster-level settings. The difference matters in disasters where the cluster itself, not just the data, needs to be reconstructed.
biology
A 20-kilogram rodent can transform a stream into a pond complex spanning hundreds of acres, and the effects persist long after the beaver is gone. Beavers are one of the most extensively studied ecosystem engineers in North American biology, and the picture has gotten substantially more complic
history
The catapult is one of the few major military technologies for which a complete invention date and inventor name are recorded. The first catapults were built around 399 BCE in the workshops of Dionysius I of Syracuse, and the engineering tradition they started ran continuously for 1800 years.
postgres
CREATE INDEX takes an ACCESS EXCLUSIVE lock for the duration of the build. On large tables that means minutes to hours of blocked writes. CREATE INDEX CONCURRENTLY trades roughly double the build time for non-blocking behavior, and the trade is almost always worth it in production.
api
Most webhook providers send every event of a subscribed type to every subscriber. Customer-side filtering wastes bandwidth and forces customers to write their own filter logic. Send-time filtering trades server complexity for substantial customer-side savings, and the trade is usually worth it.