Go to http://www.evdbt.com/papers.htm and read "The Search for Intelligent
Life in the Cost-Based Optimizer" and "How to Improve Database Performance
Using Full Table-Scans". They have very good explanations about the
situation you are facing. They are also excellent reads!
-----Original Message-----
Sent: Monday, January 06, 2003 12:49 PM
To: Multiple recipients of list 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: '[EMAIL PROTECTED]'
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
and x.col_3 in ('val1','val2','val3')
and.....
..
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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