Dynamic finite versioning: an effective versioning approach to concurrent transaction and query processing

Dynamic finite versioning (DFV) schemes that effectively support concurrent processing of transaction and queries are presented. Without acquiring locks, queries read from a small, fixed number of dynamically derived, transaction-consistent, possibly slightly obsolete, logical snapshots of the database. On the other hand, transactions access the most up-to-date data in the database without data contention from queries. Intermediate versions created between snapshots are automatically discarded. Dirty pages updated by active transactions are allowed to be written back into the database before commitment and, at the same time, consistent logical snapshots can be advanced automatically without quiescing the ongoing transactions or queries