Serializable Snapshot Isolation (SSI) research prototype by Michael Cahill, applied verbatim on top of Berkeley DB 4.6.21.
This tracks exactly what Michael implemented:
- Upstream commit:
1405db13d2e6b9e551b3b70246564f8078df5f28 - Source: github.com/michaelcahill/berkeleydb-archive
- Paper: Cahill, Röhm & Fekete, Serializable Isolation for Snapshot Databases, ACM SIGMOD 2008 (Best Paper Award).
SSI was never integrated into any released Berkeley DB; the algorithm was later adopted by PostgreSQL 9.1. This tag is preserved for historical reference.
git diff v4.6.21 v4.6.21-SSI shows precisely the 32-file change (+722/-263): new DB_TXN_SNAPSHOT_SAFE mode, DB_LOCK_SIREAD locks, rw-antidependency tracking, and snapshot-conflict detection.