OK, have bitmaps for each column value. Bitmap index, Fig. 8.18, pg. Thus RID-list can represent one row with 32 bits. Total RID-list stays the same length with 1000 column values, but Bitmap index requires a lot more space. Fast AND and OR of verbatim bitmaps speeds queries.
Parallelism speeds things.
If look up novels by Dickens, go to shelves, they're all together. If we did that with books in a library, would be hard to collect up all Dickens. Look at Figure 8.19, pg 467. Example 8.4.1 . Advantage of Clustering.