Re: how does update on table find other index blocks to maintain
From: Mladen Gogala <gogala.mladen_at_gmail.com>
Date: Sat, 6 Mar 2010 18:12:44 +0000 (UTC)
Message-ID: <hmu5us$ucn$1_at_solani.org>
On Sat, 06 Mar 2010 16:54:17 +0000, Jonathan Lewis wrote:
Date: Sat, 6 Mar 2010 18:12:44 +0000 (UTC)
Message-ID: <hmu5us$ucn$1_at_solani.org>
On Sat, 06 Mar 2010 16:54:17 +0000, Jonathan Lewis wrote:
> key value (as we see it) appear in the index ordered by rowid. So the
> same "binary chop" approach that Oracle uses to find a unique key allows
> it to find
> the specific rowid within the list of non-unique values very efficiently
> - it doesn't
> have to "check all entries" for the key.
I believe that the algorithm is commonly known as binary search and implies that the array which is searched is ordered, which is true for the rowids with the same key, within the same index.
-- http://mgogala.freehostia.comReceived on Sat Mar 06 2010 - 12:12:44 CST