Cards

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How an insert, update and delete leave live and dead row versions in the same Postgres table, the bloat after a million rows updated ten times each, and VACUUM marking dead space reusable

DatabasesDay 40Sep 9, 2026

Your Database Doesn't Delete Anything

system-design databases mvcc

Four hundred identical refund-policy questions each billed in full, beside prompt caching at the model provider and semantic caching by embedding similarity, and the 0.92 match that returns the wrong answer

AI SystemsDay 39Sep 8, 2026

The Same Question, Paid For Twice

system-design ai-systems semantic-caching

The optimal stopping problem — options arriving one at a time and gone once passed — and the 37% rule: observe the first 37% choosing nothing, then take the first option better than all of them

MathematicsSep 7, 2026

Certainty Arrives After The Gate Closes

mathematics optimal-stopping decision-making

ObservabilityDay 38Sep 7, 2026

Which Of Your Forty Services Was Slow?

system-design observability distributed-tracing

Pando, the clonal quaking aspen in Fishlake National Forest, Utah — 47,000 genetically identical trunks across 106 acres from one root system, 6,000 tonnes, with roots perhaps 80,000 years old

BotanySep 6, 2026

Forty-Seven Thousand Trunks, One Tree

botany pando aspen

A producer outpacing a consumer with the queue between them grown to two million stale messages, buffering and backpressure compared as curves, and four ways to signal a producer to slow down

ReliabilityDay 37Sep 6, 2026

Tell Them To Slow Down

system-design reliability backpressure

Work as scaffolding around a lit room — the professions that sustain life against the poetry, beauty, romance and love that Keating said we stay alive for

On LivingSep 5, 2026

Build The Scaffolding, Then Go Inside

on-living work meaning

Circuit breaker states — closed, open and half-open — beside the bulkhead pattern giving each dependency its own connection pool, and a timeline of thread exhaustion without either

ReliabilityDay 36Sep 5, 2026

Stop Calling The Thing That's Down

system-design reliability circuit-breaker

Cassandra's leaderless ring of tokens with 256 per node by default, what virtual nodes buy when adding or losing a node, and the gossip and repair cost that comes with them

Case StudyDay 35Sep 4, 2026

Cassandra Calls Them Tokens

system-design distributed-data cassandra

Three servers on a hash ring owning wildly uneven shares, and the fix — hashing each server two hundred times so six hundred small slices interleave around the ring

Distributed DataDay 35Sep 4, 2026

One Server, Two Hundred Places

system-design distributed-data consistent-hashing

Raskolnikov's theory of ordinary and extraordinary men in Crime and Punishment, the murder he commits to test it, and the suffering that becomes the verdict against his own idea

LiteratureSep 4, 2026

The Test Raskolnikov Sets Himself

literature dostoevsky crime-and-punishment

Ten shards holding ten percent of the data each while one hot key sends sixty percent of traffic to shard four, and the three fixes — cache in front, split the key artificially, replicate the hot ones

Distributed DataDay 34Sep 3, 2026

Evenly Distributed Isn't Even

system-design distributed-data partitioning

How an electric kettle switches itself off — steam rising through the handle to a bimetallic disc that bends and snaps the switch, with a second disc at the base as the dry-boil backup

PhysicsSep 3, 2026

Your Kettle Has No Thermometer

physics bimetallic-strip latent-heat

Partitioning by range against partitioning by hash, and the real question underneath both — what a single query has to touch, and whether the key keeps related rows on one shard

Distributed DataDay 33Sep 2, 2026

The Decision You Can't Undo

system-design distributed-data partitioning

Synaptic surge and pruning in early childhood — a toddler brain with twice an adult's connections, and the used pathways kept while unused ones thin away

Child DevelopmentSep 2, 2026

You're Deciding What Stays

child-development neuroscience synaptic-pruning

The rai stone money of Yap — four-ton limestone discs quarried in Palau, hauled by canoe, and one lost at sea that still counts as wealth by public agreement

EconomicsSep 1, 2026

The Fortune On The Seafloor

economics money yap

The consistency menu — strong, causal and eventual models compared with the cost of each, and a list of what can safely be eventual against what cannot

Distributed DataDay 32Sep 1, 2026

What "Latest" Actually Means

system-design distributed-data consistency

Quorum reads and writes across three replicas — W plus R greater than N, the overlapping sets that guarantee one node in every read holds the newest value

Distributed DataDay 31Aug 31, 2026

How Many Copies Have To Say Yes?

system-design distributed-data quorum

Map of the four physiographic regions of Texas with the Balcones Escarpment marked, and the elevation range from sea level on the Gulf to 8,749 feet at Guadalupe Peak

GeographyAug 31, 2026

One State, Four Countries' Worth of Ground

geography texas geology

Camus and the myth of Sisyphus — the boulder rolled up the hill forever, and the walk back down where Camus located the freedom

PhilosophyAug 30, 2026

The Walk Back Down

philosophy camus absurdism

Leader and follower replication — synchronous waiting for confirmation against asynchronous replying immediately, and a timeline showing followers landing the same write at different moments

Distributed DataDay 30Aug 30, 2026

Why Copies Disagree

system-design distributed-data replication

A rocket battery priced at $600 per kilowatt-hour broken into about $80 of cobalt, nickel, aluminium, carbon, polymers and steel, and $520 of inherited assumptions

Problem-SolvingAug 29, 2026

A Habit Wearing a Price Tag

problem-solving first-principles thinking

Password hashing compared — SHA-256 at a billion guesses a second against bcrypt and argon2, plus per-user salts that stop one cracked password revealing the next

SecurityDay 29Aug 29, 2026

The Algorithm That's Fast Is The Problem

system-design security password-hashing

B-tree versus LSM tree — updating a page in place against appending to a memtable and flushing to sorted files, with compaction as the hidden cost

Storage EnginesDay 28Aug 28, 2026

Two Ways To Write A Number Down

system-design storage-engines databases