5.7 Hot Spot Techniques
If each txn holds a lock for t seconds, then the max throughput is 1/t txns/second for that lock.
Hot spot - A data item that’s more popular than others, so a large fraction of active txns need it
- Summary information (total inventory)
- End-of-file marker in data entry application
- Counter used for assigning serial numbers
Hot spots often create a convoy of transactions. The hot spot lock serializes transactions.