Tag
mvcc
- Oct 8, 2026 Secondary Indexes Under MVCC: Version Chasing and Index Write Amplification Why every row version needs its own index entries, how a lookup follows pointers through superseded versions, and what a non-covering index costs in a versioned store. databases
- Mar 10, 2026 The Transaction ID Horizon and What Happens at Wraparound How 32-bit transaction identifiers are consumed, why freezing exists, and the sequence of failures that turns a neglected counter into a refused-write outage. databases
- Oct 24, 2025 Timestamp Oracles and Global Transaction Order How distributed systems assign a total order to transactions without a shared clock, what happens when the oracle is unreachable, and why the ordering guarantee is not the same as real-time order. distributed systems
- Sep 8, 2025 When a Snapshot Is Taken and How Commit Order Is Assigned The choice between transaction-start and first-statement snapshots, the in-progress list that defines the read view, and why a single commit counter is a shared resource. databases
- Jul 19, 2025 Heap Tuple Headers, Transaction Identifiers, and Visibility Rules How a row version records the transaction that created it and the one that deleted it, and how a reader decides whether that version belongs in its snapshot. databases
- May 10, 2025 First-Committer-Wins Validation in Snapshot Isolation How snapshot isolation validates writes against concurrent committers, why a write-write check is sufficient for its own guarantees, and the serializability it leaves on the table. databases
- Apr 28, 2025 Dangerous Structures: Detecting Serialization Cycles Under Snapshot Isolation Why snapshot isolation needs only two edge types to find every nonserializable cycle, how pivot detection works, and what the false positive rate costs. databases
- Dec 3, 2024 Vacuum Horizons, Dead Version Collection, and Table Bloat How an engine decides that a row version can never be seen again, why one old snapshot stalls collection for an entire database, and what freezing does to the identifier space. databases
- Jan 19, 2023 Undo Records and Reconstructing Older Row Versions How engines that keep only the current row in the heap rebuild earlier versions from before-images in undo segments, and what that indirection costs on the read path. databases