Re: index node split autonomy

<ctcgag_at_hotmail.com> wrote in message
news:20030525191450.694$U2_at_newsreader.com...
> Many of the concurrency/consistency concepts are demonstrated in the
Oracle
> docs with simple examples on tables, where the process has to reach into
> the undo to obtain a read-consistent view. I think I more or less
> understand this. But I'm curious about the analogous operations on
> indices. If indices never split blocks, it seems they could operate in
> pretty much the same way as tables. But then they wouldn't be much good
as
> indices, either.
>
> If an DML statement causes a index block to split, and then
> that statement rolls back, is the split also rolled back, or does
> it persist?
>
>

Hi Xho,

It persists.

Much in the same way that a bunch of inserts increments the HWM only to be rolled back. The new HWM persists..

The issue to remember here is that Oracle is a multi-user database and if an index node splits, it's quite plausible that another transaction has inserted an entry into a split node as well. If Oracle could be bothered to redo all the work involved in the split, what of the effects of other transactions ?

Cheers

Richard Received on Mon May 26 2003 - 06:51:55 CDT