Try to refer to : How the select Query Works
Can any body tell , how the sql select statement will works ? how it will come across the 3 phases 1.pharse 2.execute and 3. fetch
You must check the Oracle documentation. From high level the compress parameter works different for both versions while allocations the extents.
what is the parameter in oracle 9i and 10g for compress the dumpfile in export and import?