Re: MVCC and index-only read

On Tue, Nov 18, 2008 at 2:02 PM, Scara Maccai <m_lists@yahoo.it> wrote:
> SELECT A FROM myTAB where A <10000
>
> only uses the index (if there's an index defined for A) in Oracle.

Well, not exactly.  That's called a "covered" index because the query
could be satisfied directly from the index (the attribute is covered
by the index).  Oracle sometimes satisfies it with an index fast full
scan, but not always; it depends on the cost of other access methods
and/or what Oracle believes is currently in cache.

--
Jonah H. Harris, Senior DBA
myYearbook.com