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From "Mike Matrigali (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-5952) Need a way to determine which indexes are not used over the course of a week
Date Tue, 16 Apr 2013 16:23:17 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5952?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13632965#comment-13632965
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Mike Matrigali commented on DERBY-5952:
---------------------------------------

Just some random thoughts on this:

Could add some sort of date to be associated with ddl objects.  There are 2 interesting levels.
 Could track and maintain the info in the system catalogs for each table and index.  Or
could track and maintain at lowest level in each conglomerate.  Or could could create another
table to track this.

Note this request does not want just last used as at the low levels that would likely be updated
on each insert also.  So for this you want last used for a non-insert/update/delete statement.
 If
you are going to do this, likely should also add a last used also.

Implementation should be careful to not cause too much overhead and/or lock contention.  Updating
a system catalog can often interfere with other operations in the system.  For instance
a system doing 10000 scans a second, should likely not trying to be updating this value 10000
times.  Maybe this could only be done at compile time?  Maybe work on auto increment could
be leveraged to do quick system catalog type updates? 
                
> Need a way to determine which indexes are not used over the course of a week
> ----------------------------------------------------------------------------
>
>                 Key: DERBY-5952
>                 URL: https://issues.apache.org/jira/browse/DERBY-5952
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL, Store
>            Reporter: Dwight Carter
>            Priority: Minor
>
> We have a derby database used by a rather complex codebase.  Over time, numerous indexes
have been created on the tables.  We'd like to delete indexes which are no longer used, but
don't know how to determine that.  It would be very useful if derby provided a way to get
a list of indexes on a database which have not been used in a period of time.

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