Richard Huxton, 12.12.2007 16:12:
> Hmm - I'm not sure it does benefit that much. I mean, if you're going to
> be accessing XXXA, then XXXB, XXXC etc. in order then it clearly helps
> to have the table with the same order as your primary key. Otherwise,
> I'd be doubtful you'd see that much benefit.
>
At least for Oracle it's not mainly the order that improves the
performance, but the fact that all the data is kept in the index, so
Oracle does not need to go back to the table data after looking up the
index entry. There is no "table data" for an index-organized table in
Oracle, so only a single lookup is needed.
Thomas
