A concurrency management method called timestamp ordering employs timestamps to arrange transactions and guarantee serializability. Each transaction is given a distinct timestamp when it is initiated, which is how it operates. When the transaction is finished being executed, the timestamp is used to rank it in relation to other transactions.
This is an illustration of how timestamp ordering functions:
- Transaction 1 begins, and a timestamp of 1 is put on it.
- Transaction 2 begins, and its timestamp is set to 2.
- Transaction 3 begins, and its timestamp is set to 3.
- Data that was written by Transaction 1 is read by Transaction 2.
- New data is written in transaction 1.
- The information that Transaction 1 wrote is read by Transaction 3.
The transactions in this example are carried out in the following succession: 1, 2, 3. This is due to the fact that the timestamps attached to each transaction show the chronological sequence in which they were initiated.
Here is a timestamp ordering algorithm:
- Give each transaction a special timestamp as soon as it begins.
- Check the timestamp of a transaction against the timestamps of other transactions that have accessed the same data when it tries to read or write data.
- Wait for other transactions to finish if the transaction’s timestamp is older than those of other transactions.
- Allow the transaction to execute if its timestamp is more recent than those of other transactions.
- Use the transaction’s timestamp to rank it in relation to other transactions after it has completed.