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How to find out if an index is not being used in Oracle

Posted on 2000-06-20
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Last Modified: 2010-05-19
Is there a way to find out if an index is not being used in oracle.??
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Question by:tiger20
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sbenyo earned 50 total points
ID: 3011313
Yes.
You should run an explain plan on the query you want to check.
Explain plan shows you how oracle executes your query and what indexes are in use in the query.

To do this:

1) connect using SqlPlus.

2) run the script:

$ORACLE_HOME/rdbms/admin/utlxplan.sql

This creates the explain plan table used by oracle to create the explain plan.

2) in sqlplus:
   sqlplus>set autotrace on
   
3) Now run the query. In the explain plain oracle shows you can see if indexes are used or not.

Sample explain:

Execution Plan
----------------------------------------------------------
   0   SELECT STATEMENT Optimizer=FIRST_ROWS (Cost=1 Card=82 Bytes=
    164)

   1 0   TABLE ACCESS (FULL) OF 'DUAL' (Cost=1 Card=82 Bytes=164)

This show a table accessed without indexes (FULL).

You can also use sql trace to do that. If you want to know about it tell me.
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by:tiger20
ID: 3011419
Answer accepted
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by:tiger20
ID: 3011420
Cheers sbenyo that worked a treat.... Here the points .... enjoy :-)
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