Optimistic concurrency control: Difference between revisions

Revision as of 11:03, 23 September 2019

Revision as of 11:21, 9 February 2020

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OCC is generally used in environments with low [[Block contention|data contention]]. When conflicts are rare, transactions can complete without the expense of managing locks and without having transactions wait for other transactions' locks to clear, leading to higher throughput than other concurrency control methods. However, if contention for data resources is frequent, the cost of repeatedly restarting transactions hurts performance significantly; it is commonly thought{{who|date=July 2016}} that other [[concurrency control]] methods have better performance under these conditions.{{citation needed|date=July 2016}} However, locking-based ("pessimistic") methods also can deliver poor performance because locking can drastically limit effective concurrency even when deadlocks are avoided.

== Phases of Optimistic concurrency control ==

==OCC phases==

{{Unreferenced section|date=August 2010}}

More specifically, OCCOptimistic concurrency control transactions involve these phases:

*'''Begin''': Record a timestamp marking the transaction's beginning.