20.6. Optimistic concurrency control (OCC)
Optimistic schemes for concurrency control are based on the premise that conflict is unlikely. We should therefore be careful to avoid heavyweight concurrency control mechanisms but we must still ensure a serializable execution. OCC also aims to achieve high availability of objects. The idea is to minimize delay at transaction start. OCC is therefore appropriate for certain application areas where these conditions and requirements hold; that is, for applications which need a transaction system, but where it is unusual for different transactions to touch the same object, and which need real-time response.
For example, suppose my medical record is being updated by the hospital administration some time ...
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