Oracle-L: RE: index hint ignored?

From: Koivu, Lisa <Lisa.Koivu_at_efairfield.com>
Date: Fri, 31 Jan 2003 11:34:09 -0800
Message-ID: <F001.00540D89.20030131113409@fatcity.com>

Bah. You are right. I see the cardinality down there - 19K + records. What on earth am I thinking. <<WAKE UP, LISA>>

Have you tried adding an index on both of those columns? I'll betcha it will use a concatenated index to avoid the extra I/O.

Just a thought for a braindead Friday.

-----Original Message-----

Sent: Friday, January 31, 2003 2:32 PM
To: Koivu, Lisa; ORACLE-L_at_fatcity.com

Thanks, Lisa.

This particular table is rather small (~20,000 rows, 1.3 Mb in size, 20 distinct values for VEH_YEAR) - so it may be faster doing a FTS scan, not sure. I was mainly wondering why my hint was ignored. It's a WebSphere app (The person who wrote it is long gone!) where this statement gets executed thousands of times a day, so if I could shave some time off the query it may help...

Thanks again!

Jerry

-----Original Message-----

Sent: Friday, January 31, 2003 1:56 PM
To: ORACLE-L_at_fatcity.com; Cunningham, Gerald

Hi Jerry,

Methinks it's because this is a small table. 20 records? Peanuts. Why bother with the index.

On the same token you should probably not spend a lot of time worrying about this... unless this is just a learning exercise :)

hth

Lisa Koivu
Oracle Diaper Administrator
Fairfield Resorts, Inc.
5259 Coconut Creek Parkway
Ft. Lauderdale, FL, USA 33063

-----Original Message-----

Sent: Friday, January 31, 2003 1:31 PM
To: Multiple recipients of list ORACLE-L

Hi there.

I have a non-unique index on a table, and I'm trying to force Oracle to use the index - but it always does a FTS. Why? (I've tried it with and without the alias)

SQL> set autotrace traceonly
SQL> SELECT /*+ INDEX(A,vehicle_veh_year_indx) */ DISTINCT veh_year 2 FROM TIREADVISOR.vehicle A
3 ORDER BY veh_year DESC;

20 rows selected.

Execution Plan

0 SELECT STATEMENT Optimizer=CHOOSE (Cost=118 Card=20 Bytes=80) 1 0 SORT (ORDER BY) (Cost=118 Card=20 Bytes=80)

   2    1     SORT (UNIQUE) (Cost=67 Card=20 Bytes=80)
   3    2       TABLE ACCESS (FULL) OF 'VEHICLE' (Cost=16 Card=19607

Bytes=78428)

===

select TABLE_NAME, INDEX_NAME, COLUMN_NAME, COLUMN_POSITION from dba_ind_columns
where INDEX_OWNER = 'TIREADVISOR'
and TABLE_NAME = ('VEHICLE') order by 1,2,4,3

TABLE_NAME                     INDEX_NAME


------------------------------ ------------------------------

COLUMN_NAME          COLUMN_POSITION


-------------------- ---------------

VEHICLE                        VEHICLE_PK
VEH_ID                             1
 
VEHICLE                        VEHICLE_VEH_YEAR_INDX
VEH_YEAR                           1

Thanks for any help!

Jerry

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Author: Koivu, Lisa
  INET: Lisa.Koivu_at_efairfield.com

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Received on Fri Jan 31 2003 - 13:34:09 CST