How to make use of indexes when using group by caluse?

Question

Hi All
I am using a query with a group by caluse without any WHERE caluse.There are indexes on columns in the select clause,but the explain plan shows a full table scan.Can this be avoided and make use of indexes?
Execution Plan
   0      SELECT STATEMENT Optimizer=ALL_ROWS (Cost=347 Card=27007 Byt
          es=1053273)
   1    0   HASH (GROUP BY) (Cost=347 Card=27007 Bytes=1053273)
   2    1     TABLE ACCESS (FULL) OF 'TABLEXYZ' (TABLE) (Cost=73 Ca
          rd=27007 Bytes=1053273)
Statistics
          1  recursive calls
          0  db block gets
        317  consistent gets
          0  physical reads
        116  redo size
     373725  bytes sent via SQL*Net to client
      12351  bytes received via SQL*Net from client
       1086  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
      16268  rows processedThanks in Advance

Answer 1

user10450559 wrote:
Hi All
I am using a query with a group by caluse without any WHERE caluse.There are indexes on columns in the select clause,but the explain plan shows a full table scan.Can this be avoided and make use of indexes?In principle there are cases where Oracle can use an index range or full scan to do a group by without sorting if the "group by" columns are the leading columns in the index. But if you want an intelligent answer in your case, you will have to post the query and the definition of the index you think is the one that should be used.
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
http://www.jlcomp.demon.co.uk
"Science is more than a body of knowledge; it is a way of thinking" Carl Sagan