Engineering notes.
War stories and design decisions from building an architecture editor whose diagrams run.
Backpressure and load shedding: the two answers to overload
When demand exceeds capacity you can either push back or drop. A deep dive into backpressure (flow control for systems you own) vs load shedding (admission control at the untrusted edge), the unbounded-queue death spiral they prevent, and how to use both.
Read the post →PostGIS deep dive: how your apps actually track location
How PostGIS turns Postgres into the engine behind ride-hailing, delivery and find-nearby: geometry vs geography, SRID 4326, the GiST index, ST_DWithin vs ST_Distance, the KNN operator, and geofencing.
The four disaster-recovery tiers, on one axis
Backup & restore, pilot light, warm standby, hot standby — what each buys in RTO and RPO, what it costs, and how to choose the right tier per workload instead of per company.
Multi-tenancy: every model, from single-tenant to cells
The full taxonomy: single/multi/hybrid deployment, the silo-pool-bridge vocabulary, the data-layer ladder (shared tables to cells), compute tenancy, and why vertical SaaS chooses differently than horizontal.
Quorum: the childhood arithmetic that stops split-brain
Why any two majorities must overlap, what happens when the network splits 3/2, R+W>N as a dial, and the practical rules: odd cluster sizes, three failure domains, witness nodes, flexible quorums.
Two-phase commit: how it works, and the moment it blocks
The classic protocol for atomic transactions across systems — prepare and vote, then commit. Plus the famous failure: the in-doubt participant, the latency tax, heuristic outcomes, and why modern databases run 2PC over consensus groups.
Hot shards and hot keys: when perfect hashing can't save you
One viral key can melt one machine while fifteen shards idle. Why adding shards does nothing, and the mitigation ladder: detection, hot-key caching, key salting, bounded-load rebalancing, whale isolation.
Every consistency model, explained with one diagram
Linearizable, sequential, causal, session guarantees, eventual and tunable quorums — what each one promises, what it costs, and why consistency is a property of the read path, not the database.
Federated query engines: one SQL query, four databases, zero ETL
How Trino-style engines join data across Postgres, MySQL, a data lake and a SaaS API without moving it first — pushdown, connectors, and the trade-offs.
Hinted handoff: how a write succeeds while its replica is dead
The pattern that lets Cassandra and Dynamo-style stores keep accepting writes through node failures — and the read-consistency trap hiding inside it.
mTLS without secrets: workload identity with SPIRE
How SPIFFE/SPIRE gives every service a cryptographic identity — attestation, short-lived SVIDs, and mutual TLS where neither side holds a long-lived secret.
Our simulation engine bans Date.now() and Math.random()
Total determinism is the load-bearing feature of techdiagrams.net — how a virtual clock and a seeded PRNG make every architecture failure replayable byte-for-byte.
Raft, explained with one diagram: how clusters agree on anything
Leader election, log replication and the majority commit rule — the consensus algorithm behind etcd, Consul and CockroachDB, walked through visually.
Merkle trees: how replicas find a needle of difference in a haystack of data
Why Cassandra, DynamoDB and git can compare gigabytes by exchanging kilobytes — the hash tree that powers anti-entropy repair, visually explained.
Our AI copilot is two AIs — and one exists to argue with the other
Why the techdiagrams.net design copilot uses a designer model and a cross-vendor judge model, and why the AI is never allowed to touch your diagram directly.
The React bug that silently ate my users' text
Save on blur" is a contract with the DOM — and unmounting an input breaks it without telling you. A debugging story from building techdiagrams.net.
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