Choose two.
Which two are true about poorly performing SQL statements and their tuning in Oracle database instances?
A.SQL statements performing many physical I/Os can always have their performance improved by creating indexes. B.The solution that best optimizes one SQL statement can degrade the performance of others. C.SQL statements doing joins always do more physical I/O than single table queries. D.Poorly performing SQL statements can be tuned automatically by the Oracle server. E.SQL statements doing only logical reads never require tuning because they do no physical I/O.正确答案BD
