David Snelling
a859d6ecf8
The MVCC time-travel layer kept nounChains/verbChains as unbounded Map<id, number[]> — one resident chain per id ever touched across retained history (O(N) RAM, defeating billion-scale time travel). Replace with a hot-tail window + bounded cold LRU + a mutex-free bulk resolver, keeping resolveAt exactly correct. The most-recent W generations stay resident as full chains (the common recent-pin read is O(log), zero scan); deeper pins reconstruct one id's chain on demand into an L-bounded LRU. Reconstruction is LOCK-LIGHT — it holds no commit mutex, so a historical read never stalls writers; correctness holds because a live pin's answer is always > minPinnedGeneration, which compaction can never reclaim, and a concurrently-reclaimed gen below that is skipped. materializeAtGeneration routes through a new mutex-free resolveManyAt (one forward pass, O(R + |ids|)) — without it a deep-pin materialize both regresses to O(N*R) and deadlocks on snapshotWith's mutex. The cold cache is invalidated on re-touch to stay coherent. Resident RAM is O(W*d + L), independent of N. 11-case test (oracle-vs-bruteforce, held-Db across eviction + concurrent compaction, no-deadlock, write-path I/O-free); unit 1735 + integration 613 (db-mvcc/db-temporal/db-asof green). |
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| .. | ||
| bounded-chains.test.ts | ||
| db-portable-graph.test.ts | ||
| generation-chain.test.ts | ||
| generationStore.test.ts | ||
| stableEqual.test.ts | ||
| whereMatcher.test.ts | ||