Is index range scan the reason for query running long time

Question

I would like to know whether index range scan is the reason for the query running long time. Below is the explain plan. If so, how to optimise it? Please help
Operation     Object     COST     CARDINALITY     BYTES
SELECT STATEMENT ()          413     1000     265000
COUNT (STOPKEY)                    
FILTER ()                    
TABLE ACCESS (BY INDEX ROWID)     ORDERS     413     58720     15560800
INDEX (RANGE SCAN)     IDX_SERV_PROV_ID     13     411709     
TABLE ACCESS (BY INDEX ROWID)     ADDRESSES     2     1     14
INDEX (UNIQUE SCAN)     SYS_C004605     1     1     
TABLE ACCESS (BY INDEX ROWID)     ADDRESSES     2     1     14
INDEX (UNIQUE SCAN)     SYS_C004605     1     1     
TABLE ACCESS (BY INDEX ROWID)     ADDRESSES     2     1     14
INDEX (UNIQUE SCAN)     SYS_C004605     1     1

Answer 1

The index range scan means that the optimiser has determined that it is better to read the index rather than perform a full table scan. So in answer to your question - quite possibly but the alternative might take even longer!
The best thing to do is to review your query and check that you need every table included in the query and that you are accessing the tables via the best route. For example if you can access a table via primary key index that would be better than using a non-unique index. But the best way of reducing the time the query takes to run is to give it less tables (and indexes) to read.
John Seaman
http://www.asktheoracle.net