Iain,
I will do some tests. Theoretically, yes, a range scan should be better
than a full table scan.
Thanks for your helpful recommendation.
Cherie
"Nicoll, Iain
(Calanais)" To: "'[EMAIL PROTECTED]'"
<[EMAIL PROTECTED]>
<iain.nicoll@cal cc: "'[EMAIL PROTECTED]'"
<[EMAIL PROTECTED]>
anais.com> Subject: RE: SQL Tuning - How to avoid
TOCHAR function against a date
04/08/02 12:37
PM
Cherie,
Couldn't you do
SELECT DATE_KEY
FROM DATE_DIM
WHERE ORACLE_DATE >= trunc(:b1)
and oracle_date < trunc(:b1) + 1
which should at least give a range scan.
Iain Nicoll
-----Original Message-----
Sent: Monday, April 08, 2002 6:57 PM
To: Multiple recipients of list ORACLE-L
I've got the following SQL statement that is running very long on a nightly
data load. The problem is the TO_CHAR function which is preventing
me from using the index on this small (20,000-row table).
This is an 8.0.4 database so it is not possible for me to use
make this a function-based index.
The problem is that the date field has minutes, etc. included and
those need to be eliminated before the comparison can be made.
That's why I can't just eliminate the TO_CHAR from both sides
of the equation.
Isn't there a way that I can pull this function out of the select statement
and do it in a preceeding statement? Then I could just pass in both
variables to this statement without the TO_CHAR and use my index.
Is this realistic? How, exactly could it be done?
SELECT DATE_KEY
FROM DATE_DIM
WHERE TO_CHAR(ORACLE_DATE,'DD-MON-YYYY') =
TO_CHAR(:b1,'DD-MON-YYYY')
SQL> desc date_dim;
Name Null? Type
------------------------------- -------- ----
DATE_KEY NOT NULL NUMBER(5)
ORACLE_DATE NOT NULL DATE
DATACOM_DATE NUMBER(6)
DATACOM_REVERSE_DATE NUMBER(6)
DAY_OF_WEEK NOT NULL VARCHAR2(30)
DAY_NUMBER_IN_MONTH NOT NULL NUMBER(3)
DAY_NUMBER_OVERALL NOT NULL NUMBER(9)
WEEK_NUMBER_IN_YEAR NOT NULL NUMBER(3)
WEEK_NUMBER_OVERALL NOT NULL NUMBER(7)
MONTH NOT NULL VARCHAR2(30)
MONTH_NUMBER_OVERALL NOT NULL NUMBER(7)
YEAR NOT NULL NUMBER(5)
WEEKDAY_IND NOT NULL CHAR(1)
LAST_DAY_IN_MONTH_IND NOT NULL CHAR(1)
DATA_WAREHOUSE_MOD_DATETIME NOT NULL DATE
DATA_MART_MOD_DATETIME NOT NULL DATE
SQL> select oracle_date from date_dim where rownum=1;
ORACLE_DA
---------
01-JAN-70
Thanks in advance for any help.
Cherie Machler
Oracle DBA
Gelco Information Network
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