Re: Column order in indices (oracle 9.2)

  • From: "goran bogdanovic" <goran00@xxxxxxxxx>
  • To: genegurevich@xxxxxxxxxxxxxxxxxxxxx
  • Date: Tue, 1 Aug 2006 15:03:32 +0200

Pay also attention if some of those columns has been used in the where
clause with a range condition.
If such, put this column(s) at the end of the index. The reason why, you can
find in the book of J.Lewis.
CBO walk the mysterious ways :-)

On 8/1/06, Schultz, Charles <sac@xxxxxxxxxxxxx> wrote: 

The column order does matter, but Oracle can SKIP SCAN an index in the
situation you talk about. To determine exactly what is going on, you
should at least get an explain plan of your sql. I imagine there are
other factors involved.

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of
genegurevich@xxxxxxxxxxxxxxxxxxxxx
Sent: Tuesday, August 01, 2006 7:44 AM
To: oracle-l
Subject: Column order in indices (oracle 9.2)

Hi everybody:

I remember reading that in Oracle 9.2 and higher the order of the
columns in an index does not matter.
That is oracle will be able to quickly search on a column even if it is
not a leading one. I have a table with a primary key consisting of three
columns. When a table is queried based on the third column, the data
start coming out immediately, but when I use the second column the query
just sits there.
Is that an expected behavior? Did I misunderstood something about the
column order?

thanks for any insight

Gene Gurevich


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