RE: Validate index

But an online validation will not populate index_stats which would be useful
for finding indexes with poor space usage chrematistics.  Being that this is
the whole point of running validate index in this case I think the best
alternate is to manually calculate the space requirement of the index and
then compare this to the actual usage.  If the index is twice the calculated
requirement then it is probably worth rebuilding from a space management
point of view.  Rebuilding will not help select performance and could harm
insert performance if the indexed column values repeat.  Repeating keys
would have to go into existing, probably full, blocks causing block splits.
Assigning an adequate pct_free on the rebuild would help avoid this problem.
But when disk space is limited reclaiming space can become a required
activity.

IMHO -- Mark D Powell --


-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Feighery Raymond
Sent: Friday, August 06, 2004 9:55 AM
To: 'oracle-l@xxxxxxxxxxxxx'
Subject: RE: Validate index


ANALYZE ... VALIDATE INDEX will put a shared lock on the table preventing
DML.
Unless you are using 9i or later, when you can use the ONLINE option.

Impact: it depends.

Ray

-----Original Message-----
From: jaysingh1@xxxxxxxxxxxxx [mailto:jaysingh1@xxxxxxxxxxxxx]
Sent: Friday, August 06, 2004 2:38 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: Validate index


Hi All,

Does validate index (pk index) enforce any exclusive lock on the table?

The reason I am asking is that we are trying to validate few indexes(to find
out fregmentation) on production (while the site is live). What could be the
impact on parent table?

Thanks
Sami

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