> COALESCE would be a better option than REBUILD for Indexes on
> monotonically increasing sequences where older values are purged periodically.
Unless you happen to be doing index_ffs on that particular index, in which
case a rebuild *may* be in order. Rebuilding the index may cause insert
performance problems for a time due to block splits.
If the index is a composite index with some other non-unique value(s)
making up the index, a higher than normal number of block splits may be
in your future. I haven't tested the composite index yet, but this seems reasonable.
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
|
To: Multiple recipients of list ORACLE-L <[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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