Jared,
I don't see how index skip scans could benefit more
from a rebuild than from coalesce (providing the index height remains the same).
Skip scan doesn't scan the whole index like FFS does, it just does several scans
for each value set in beginning of concatenated index (+some more
mechanisms).
Maybe I'm missing something here, what did you have
in mind?
Tanel.
If the index is
based simply on the unique key, and for some reason you are
using index_ffs on it, then rebuilding will
cut down the number of scanned blocks. It would be interesting to see how skip scans are affected by this as
well. Jared
| Hemant K Chitale
<[EMAIL PROTECTED]> Sent by: [EMAIL PROTECTED]
11/01/2003 12:34 AM
Please respond to ORACLE-L
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<[EMAIL PROTECTED]> cc:
Subject: RE: re Rebuilding Indexes in
Oracle Apps -- an update | Richard et al,
{for those who've been
following the thread on Rebuilding Indexes ...}
I've just been reading
the AskTom thread on rebuilding indexes at
http://asktom.oracle.com/pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:6601312252730
and
picked on the important line "Coalesce... reclaim the free space from
mostly empty index leaf blocks that will not be reused otherwise due to
your increasing sequence. "
Richard has also pointed COALESCE as a
better option. COALESCE would be a better option than REBUILD for Indexes
on monotonically increasing sequences where older values are purged
periodically.
Hemant K Chitale Oracle 9i Database Administrator
Certified Professional My personal web site is :
http://hkchital.tripod.com
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