What "Concurrent" Actually Means
Why concurrent writes survive even a strict quorum, why last-write-wins is only safe for keys you never rewrite, and why two operations minutes apart can still be concurrent.
#consistency
The Limits of Quorum Consistency
Why w + r > n is a probability dial rather than a guarantee — the edge cases that return stale data anyway, the consistency guarantees quorums never provide, and why staleness is so hard to monitor.
Replication: What We've Learned
Closing the Database Replication series — the four reasons to replicate, the three approaches side by side, and the one trade-off that turns out to be underneath all of them.
Version Vectors, Siblings, and Tombstones
How a database tells an overwrite from a conflict — the version-number algorithm behind siblings, why merging by union resurrects deleted items, and what a version vector adds once there is no single replica.
Consistency Guarantees Under Lag
Two more subtle problems caused by replication lag — monotonic reads and consistent prefix reads — and the approaches that address all three consistency guarantees together.
Replication Lag: The Hidden Cost
What happens when asynchronous replication lets followers fall behind — and the first concrete problem it causes: reading your own writes.