Topic
Version-column locking, lost-update anomalies and OptimisticLockException semantics when writes bypass the ORM's version tracking.
Sekiban DCB's Decider template ships three worked feature slices for an agent to copy. In this walkthrough, review, implementation, build, concurrency tests on a real PostgreSQL database and UI fixes took under an hour.
Reality
A GCP walkthrough put Spark, Trino and BigQuery on the same orders table through Google's Iceberg REST catalog. The 409 ConflictException it logged is the part of the demo a production pipeline has to plan for.
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A dev.to post-mortem's request log puts 89 milliseconds between the guard read and the paid write, and the second request's retry landed its charge more than four seconds after the row already said paid.
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Doco's MCP server gives Claude Code a version fingerprint on every read and rejects any write built on a stale one. This is a first-party tutorial. The transferable part is the RFC 9110 precondition underneath it.
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A four-part dev.to walkthrough of leases, fencing tokens and consensus ends where it should. Coordination is a cost, and the cheaper fix is usually a unique index or a version column.
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A dev.to writeup traces two weeks of low-looking referral counts to a @Modifying increment that never bumped @Version, letting one stale save() overwrite the counter.
Reality