1Z0-054 Question #19: Real Exam Question with Answer & Explanation

Examine the initialization parameter values for the instance given below: NAME TYPE VALUE ------------------------------------ ----------- ------------------ optimizer_capture_sql_plan_baselines boolean FALSE optimizer_dynamic_sampling integer 2 optimizer_features_enable string 11.1.0.6 optimizer_index_caching integer 0 optimizer_index_cost_adj integer 100 optimizer_mode string ALL_ROWS db_file_multiblock_read_count integer 64 You notice that the one of the queries is using a full table scan (view Exhibit1) instead of index unique scan (view Exhibit2). The index is present on the column that is accessed in the WHERE clause of the query. The cost for a full table scan is more than that for an index unique scan. Why would the optimizer choose full table scan over index unique scan? (Choose all that apply.)