RE: Indexing a partitioned column

From: Jack C. Applewhite <japplewhite_at_inetprofit.com>
Date: Fri, 13 Jul 2001 11:58:31 -0700
Message-ID: <F001.0034A107.20010713105551@fatcity.com>

Rich,

It depends... Is Fiscal_Year truly just the year, or is it a full Date column?

If it's just the year, then an index would be of no benefit, since all rows in each partition would have the same value. A query that included ..."Where Fiscal_Year = 1999" would hit the right partition because the optimizer would recognize the partition key being referenced - no index needed.

If Fiscal_Year is a Date column and queries include something like ..."Where Fiscal_Year Between To_Date('19990713','YYYYMMDD')And To_Date('19990714','YYYYMMDD')" then a local index would be useful. The optimizer would point the query to the 1999 partition and the local index would facilitate fetching the appropriate rows there.

Jack

Jack C. Applewhite
Database Administrator/Developer
OCP Oracle8 DBA
iNetProfit, Inc.
Austin, Texas
www.iNetProfit.com
japplewhite_at_inetprofit.com
(512)327-9068

-----Original Message-----
Sent: Friday, July 13, 2001 12:31 PM
To: Multiple recipients of list ORACLE-L

Hi all,

So there I am, partitioning a 7M+ row table by FISCAL_YEAR. There is currently an index on FISCAL_YEAR that I had planned to drop, but I can't seem to find anything to back up my assumption that the index would no longer be needed, and would in fact slow down access to the table. I've done some explain plan comparisons that look good to me, but I'd like some outside force to say "Yay", "Nay", or "RTFM in the Oracle yadda-yadda for 8.1.7".

Anyone?

Rich Jesse                          System/Database Administrator
Rich.Jesse_at_qtiworld.com             Quad/Tech International, Sussex, WI USA

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Author: Jack C. Applewhite
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Received on Fri Jul 13 2001 - 13:58:31 CDT