Re: MVCC and index-only read

On Tue, Nov 18, 2008 at 12:33 PM, Thomas Kellerer <spam_eater@gmx.net> wrote:
> If all the columns from the select list are available in the index, then
> Oracle will always prefer the index scan over a table scan (at least I have
> never seen something else). Even for a SELECT that returns all rows of the
> table.
>
> They are taking this concept even further with index organized tables, where
> no real "table data" exists, everything is stored in the index (quited nice
> for e.g. link tables that only consist of two or three integer columns)

Sounds like they're borrowing the code from innodb that does much the
same thing.  In Innodb, if a field is indexed, it lives only as an
index, not in the table and an index at the same time.