Author Topic: Oracle DBA Question 73  (Read 60 times)

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Offline ralph0595

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Oracle DBA Question 73
« on: April 24, 2009, 01:32:48 PM »
Question:
The credit controller for your organization has complained that the report she runs to shows customers with bad credit ratings takes too long to run. You look at the query that the report runs and determine that the report would run faster if there were an index on the CREDIT_RATING column of the CUSTOMERS table.
The CUSTOMERS table has about 5 million rows and around 100 new rows are added every month. Old records are not deleted form the table.
The CREDIT_RATING column is defined as a VACHAR2(5) field. There are only 10 possible credit ratings and a customers\'s credit rating changes infrequently. Customers with bad credit ratings have a value in the CREDIT_RATINGS column of \'BAD\' of \'F\'.
Which type of index would be best for this column?

A. B-Tree
B. Bitmap
C. Reverse key
D. Function-based

Answer: B
Bitmap index is the best index to use with low cardinality data and large amount of rows. It works excellent for the data with infrequent changes.

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Oracle DBA Question 73
« on: April 24, 2009, 01:32:48 PM »

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