RE: unexpected query plan

  • From: "Polarski, Bernard" <Bernard.Polarski@xxxxxxxxxxxxxx>
  • To: <Christian.Antognini@xxxxxxxxxxxx>,<paul.baumgartel@xxxxxxxxxxxxxxxxx>
  • Date: Tue, 23 Jan 2007 08:39:14 +0100

The link is broken for me. Nevertheless for those interested in the
subject here is a good resource from W. Breitling that explain it:
http://www.centrexcc.com/What%20is%20new%20in%20the%20Oracle%209i%20CBO.
ppt.pdf 

Bernard Polarski
Oracle DBA

-----Original Message-----
From: Christian Antognini [mailto:Christian.Antognini@xxxxxxxxxxxx] 

Paul

> What is this indexjoin operation?  

To save a table access the query optimizer is able to get the data by
joining two indexes on the same table (based on the ROWID that can be
found in both segments). Of course this is only possible when all
referenced attributes are indexed.

> I have never seen it.  

FYI: this is not something "new". Here a link to the 8.1.5 where it is
documented...
http://download-uk.oracle.com/docs/cd/F49540_01/DOC/server.815/a67781/c2
0b_ops.htm#1164


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