| index..? [message #117267] |
Tue, 26 April 2005 03:16  |
sunil_v_mishra
Messages: 506
Registered: March 2005
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Senior Member |
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hi
can any one tell me where exactly index are stored and for which column i have to create index for a table on which FTS take place.
From:- sunil
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| Re: index..? [message #117332 is a reply to message #117267] |
Tue, 26 April 2005 10:01  |
smartin
Messages: 1803
Registered: March 2005
Location: Jacksonville, Florida
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Senior Member |
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Read the oracle performance tuning guide. In it you'll find descriptions of things like explain plan that will tell you how a query is being processed, and ways to determine candidate fields to be indexed. Primary keys and Unique constraints will have indexes to enforce the constraints. You probably will want indexes on all of your foreign keys (or at least that is a reasonable starting point). Full table scans are not always bad, particularly when you are retrieiving and processing large volumes of data. But if you are doing mostly operations where you only need a single row at a time per user action, then an index may prove very helpful. There is an overhead to maintaining updates, inserts, and deletes on fields with indexes, so it is generally a trade off between modifications and reads, and which your particular area of your system needs to optimize at the expense of the other.
Not sure what you mean by where to store them...they go in tablespaces just like everything else?
And I'd like to repeat that I think it would be very helpful for you to do some more reading. Actually the concepts guide might be the best bet for you to start with, just pick it up and read it front to back, or at least read the chapters that cover what you are doing first and read the rest later.
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