Re: Tracking usage of index

  • From: Mladen Gogala <gogala.mladen@xxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Thu, 26 Nov 2020 17:28:33 -0500

Hi Lok,

You can turn on monitoring for index, something like "ALTER INDEX PK_EMP MONITORING USAGE". The usage will be in V$OBJECT_USAGE. Unfortunately, there is no owner in that table, so you need to log in as the index owner.

Regards

On 11/26/20 3:19 PM, Lok P wrote:


We have just moved from Oracle version 11.2.0.4 to 19.3. And also we were on HP and now we moved to Exdata-X5. And the team is asking to verify if some of the indexes are actually not in use as we are in Exadata and thus we can drop them afterwards. So was trying to understand the reliable way to achieve the list of unused indexes?

As per my understanding 11.2.0.4 was having option for setting the monitoring On for the specific indexes, to see its usage from dba_object_usage, but that was just a "YES" or "NO" flag which was not of much help(as amount of usage is also not captured there) and also stats gathering on the index was making the usage flag to YES which is wrong, also indexes on foreign key were not getting picked up as USED in cases.

But i see starting from version 12.2+ , Oracle is by-default capturing all the information in a new view DBA_INDEX_USAGE, so wanted to understand from experts if this is safe and reliable way to collect index usage information or if we have anything new on 19C more reliable for finding index usage?

--
Mladen Gogala
Database Consultant
Tel: (347) 321-1217

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