Databases Reference
In-Depth Information
Delete:
As with ordinary disks, the cost of a delete operation is similar to that of
an insert operation. The costs of a delete operation with synchronous backup,
asynchronous backup, and index-cached asynchronous backup are:
Retrieve:
The following are the response times for a retrieve operation without
and with index caching:
3.2.3
Comparisons of Estimated Costs
We now compare the cost of an insert, a delete and a retrieve operation using
autonomous disks with those using ordinary disks. For a given operation, for
instance an insert operation, the costs of disk accesses are equivalent between
autonomous disks and ordinary disks under the same condition:
Thus, only
the costs related to communication are different. The same argument applies to
delete and retrieve operations. By considering their operations, this is easily
understood.
We now estimate response times for those operations by substituting some
practical values for the variables in the previous cost formulas. Using these
