Optimistic concurrency control protocols in real-time database, real-time database variants of optimistic concurrency control (OCC) protocols, OCC-Broadcast Commit, OCC-Sacrifice, OCC-Wait, and Wait-50 protocols
Optimistic Concurrency Control Protocols
They follow a concept called
validation (or certification) of transactions’ operations. This validation is
done at the end of the transaction. As the name suggests, these protocols do
not prevent any transactions from accessing any data items they require. The idea
is to check all the necessary formalities at the end of the transaction before
commit.
In optimistic concurrency control, any
numbers of concurrent transactions are permitted (even some of the transactions
work on same data items). The conflict of transactions, i.e., read-write,
write-write on same data items, is validated at the end of the transaction. If any
conflict is found during validation, the victims are chosen and rolled back. This
avoids the unnecessary blocking of resources.
The following are the variants of OCC
protocol where the classical OCC algorithm is slightly changed to accommodate
real-time database environments;
- OCC – Wait
- Wait – 50
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