Re: HowTo find out used (useful) and unused (usesless) indexes?

From: Shakespeare <>
Date: Sun, 20 Apr 2008 10:05:17 +0200
Message-ID: <480af934$0$14354$>

"DA Morgan" <> schreef in bericht
> Shakespeare wrote:
>> But an index may become useful over time, true?
>> Shakespeare
> On that basis alone one could justify putting an index on every
> column of every table so I will respectfully disagree unless you
> write a very broad definition of "may."
> You need to understand your data and how it is being accessed.
> The extra overhead of an unused index is not value added.
> My recommendation would be to use the DBMS_STATS.SET.... procedures
> to see how queries will react to the expected future growth of both
> tables and indexes.
> --
> Daniel A. Morgan
> Oracle Ace Director & Instructor
> University of Washington
> (replace x with u to respond)
> Puget Sound Oracle Users Group

I was aiming at data with for example a 'year' column. This column could be indexed by design, but in the first year (all records same value) this index is not useful and won't be used. But on the first entry in the second year it is useful to find entries of that year and so on. A script to remove or disable unused indexes would remove/disable this index in the first year.

Shakespeare Received on Sun Apr 20 2008 - 03:05:17 CDT

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