Oracle 9i Modifying settings in favour of Index scans

In a normal setting CBO in Oracle 9i gives equal preference to index scans and full table scans.But it is possible for the administrator to tweak the settings so as to make the optimiser favour index scan to full table scan.

optimizer_index_cost_adj is the parameter used for the purpose.By default its value is 100.Here it gives equal weightage to index scan as well as full table scan.By bringing that value down the CBO prefers for a index scan to full table scan.The value can range between 1-10000.