RE: Difference in speed of sorting using index and non-index colu

KC:  

In some cases, Oracle can use an index to read the data in sorted order, thereby eliminating the need for the SORT operation. Check your EXPLAIN PLANs. If there is a SORT step listed, then Oracle is doing a sort, if not
(and there is a ORDER BY clause on your query) then Oracle is using the
index to read the data in sorted order.  

Kevin

-----Original Message-----
Sent: Tuesday, June 05, 2001 10:21 AM
To: Multiple recipients of list ORACLE-L the order by

Dear list,  

Someone ask me when Oracle is doing a sort, will it make a difference if we use indexed column and non-indexes column in the order by clause, my initial thinking was index only speed up the retrieval of data from disk, Oracle probably using other algorithm in sorting records, so indexing is not relevant in that case. Can someone shed light on this question.  

KC

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Author: Toepke, Kevin M
  INET: ktoepke_at_cms.cendant.com

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