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Also, even if 2 queries have an identical cost _AND_ explain plan that does not mean they'll execute in the same amount of time! (At least with Oracle 8.1.6, 8.1.6 & 8.1.7 on Sun Solaris)
Yes, I have tested this and No I can't explain it.
The specific situation was somthing like this: Original:
SELECT id FROM credit_card WHERE credit_card_number = :ccn; Modified: SELECT /*+ FIRST_ROWS */ FROM credit_card WHERE credit_card_number = :ccn;
The hinted query ran about 10-15% faster (over thousands of executions) than the unhinted version. The credit_card table was hash partitioned on credit_card_number.
Caver
-----Original Message-----
Sent: Wednesday, December 12, 2001 4:55 AM
To: Multiple recipients of list ORACLE-L
For the SAME query, the costs can be compared - but remember that the cost is basically just a mathematical algorithm that pops out a number at the end. It is somewhat analagous to the number of IO's expected to satisfy the query, but of course
hth
connor
"Some days you're the pigeon, some days you're the statue"
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