| Index or Hint, which one is efficient? [message #23511] |
Fri, 13 December 2002 15:22  |
Reddy Peram
Messages: 52
Registered: December 2002
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Member |
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I have an index on 5 columns for a tableA. I am using the first 4 columns in the Where clause in an UPDATE statement to update tableA.
Creating a new index on 4 columns OR forcing an optimizer to use the existing index, which one is more efficient?
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| Re: Index or Hint, which one is efficient? [message #23512 is a reply to message #23511] |
Fri, 13 December 2002 15:37  |
Todd Barry
Messages: 4819
Registered: August 2001
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Senior Member |
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I'm assuming your stats are current and the optimizer is still not using the index in question. You could add a hint - certainly don't add another index - but I would recommend to first adjust the optimizer_index_cost_adj setting (the default of 100 is way too high) and checking the plan.
You can adjust this at the session level (alter session set optimizer_index_cost_adj = 5) and then set it in init.ora once you have found a suitable value. Don't be concerned with a low value - my systems run with a value of 1.
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