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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Prevent FTS
Read Tim Gorman's The Search For Intelligent Life in the Cost-Based Optimizer. I think its on his website - http://www.evdbt.com/papers.htm
Babu
manoj.gurnani_at_orb
itech.co.in To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
Sent by: cc:
root_at_fatcity.com Subject: RE: Prevent FTS
01/06/03 02:49 PM
Please respond to
ORACLE-L
What is the significance of parameter OPTIMIZER_INDEX_COST_ADJ ? When I tried to change the value the explain plan has changed .
alter session set OPTIMIZER_INDEX_COST_ADJ = 10
table access for Z was by index rowid
alter session set OPTIMIZER_INDEX_COST_ADJ = 100
table access for Z was full
How can I make effective use of this parameter .
If i dont want to use this in alter session,can this value be
set elsewhere.
what is the difference between setting this parameter to some other value
than
default
compared to using hints in sql stmt.
I've tried some hints like rowid,index but it did not work for the join
stmt
as it still used the FTS of Z before I tried to change the above parameter
to
10.
-----Original Message-----
Sent: Monday, January 06, 2003 11:03 PM
To: 'ORACLE-L_at_fatcity.com'
Hi All,
I've 3 tables table x,y,z
pk of x is (col_1,col_2),pk of y is (col_1,col_2,col_4,col_5),pk of z is
(col_1,col_2)
where clause is :
where x.col_1 = y.col_1
and x.col_2 = y.col_2 and x.col_1 = z.col_1 and x.col_2 = z.col_2 and y.col_1 = z.col_1 and y.col_2 = z.col_2
Explain plan shows that there is a FTS of table z . what can be the reason for this and how to prevent this.
Thanks
Manoj
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