Re: 8 and 8i default constraint behavior

In a unique index, the rowid is stored
in a fixed location at the start of row. In a non-unique index, the rowid is
appended to the index as a real column,
so it has to have a length byte prepended; Oracle then treats the index as a unique index using all the normal tools for handling a string of (length)(value) pairs.

Here's another trivium (which I think is the singular of trivia) on indexes -

    The rowid stored in an index is 6 bytes,     unless it is a global index for a partitioned     object, in which case the rowid is actually     stored as 10 bytes (4 more bytes for the     object-id).

--
Jonathan Lewis
Yet another Oracle-related web site:  http://www.jlcomp.demon.co.uk

Practical Oracle 8i:  Building Efficient Databases
Publishers:  Addison-Wesley

Reviews at: http://www.jlcomp.demon.co.uk/book_rev.html



Howard J. Rogers wrote in message <3af93719_at_news.iprimus.com.au>...


>See, I knew you'd know!!

>

>Thanks Jonathan!  (Incidentally, what's the extra byte?)

>

>Regards

>HJR

>