Key Range Locking Strategies for Improved Concurrency
نویسنده
چکیده
“Phan~oma” are records inserted into a concurrently aelected set of records specified by a predicate such that Ihe selection does not eee a transaction conaietent result. The usual locking slrategy is lo lock only czisling records. However, records that satisfy the eeleclion predicate muat be locked even when they are nol present in the database to prevent their insertion. One way to cope with phantoms is through range locking, 4 limited form of predicate locking. We investigate lock modes for ranges and describe new lock modes lhal greatly increase concurrency. We explore locking strategies involving range, key, and record resources that permit trade-offs between concurrency and lock overhead.
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