What could be the reason?
A. because the histogram statistics for the COUNTRY_ID column are not updated
B. because the DB_FILE_MULTIBLOCK_READ_COUNT initialization parameter is set to a high value
C. because the optimizer calculates the cost of accessing blocks by using a full table scan to be less as compared to index scans, even though indexes are available
D. because indexes on CUST_GENDER and COUNTRY_ID columns are of different types, the index on the CUST_GENDER column is bitmap index, and on COUNTRY_ID columns is btree index.
Answer:C
What could be the reason?
A. because the histogram statistics for the COUNTRY_ID column are not updated B. because the DB_FILE_MULTIBLOCK_READ_COUNT initialization parameter is set to a high value C. because the optimizer calculates the cost of accessing blocks by using a full table scan to be less as compared to index scans, even though indexes are available D. because indexes on CUST_GENDER and COUNTRY_ID columns are of different types, the index on the CUST_GENDER column is bitmap index, and on COUNTRY_ID columns is btree index.