Table data on disk normally is read from a global buffer (or a local buffer) one page at a time. However, this data can also be read in batches of multiple pages, rather than one page at a time. This capability is provided by the prefetch facility. By using the prefetch facility, you can reduce the number of I/O operations between the table data on disk and the global buffer (or local buffer).
The prefetch facility is available when the following conditions are satisfied: