Unit 10, Section 13: Database Scan Utility

Generally, the Database Scan utility’s performance characteristics are like HD Unload: both utilities read databases in a block-by-block manner and periodically need to re-read blocks that have already been read because segments are not stored in their Most Desirable Block.  Having many additional buffers will not help except for those hierarchically later segments that are physically stored in blocks/CIs that were already processed.