Oracle Core: Essential Internals for DBAs and Developers

Working Data Sets

So we’ve reached an important unit of memory, a collection of buffers that underpins the physical I/O behavior in Oracle. I emphasize the word physical because the mechanisms for finding and visiting buffered data (i.e., the so-called “logical” I/O) introduce a whole new pattern that cuts right across the buffer pools and working data sets . . . but we’ll come to that in a while.

Note In all the discussion to date, I have been ignoring the options for direct path reads and writes—I/O that goes to and from private process memory rather than the shared memory area. Actions that take place in private are not particularly complex, ...