If the number of leaf blocks of index , scanned is less than 5000 then degree of parallelismis 2?

If the number of leaf blocks of index , scanned is 50000-250000 then what is the degree of parallelism is 16 ?

NOLOGGING is used to reduce redo log generation ?

EXPORT_TABLE_STATS procedure is used to export statistics of an existing table ?

If the serial code runs in less than 50% window time than parallelism should be considered ?

The purpose of comments is that someone that has never worked on the project before. They would need to underderstand precisely where changes has been done, why those changeswere made, and exactly what the change was.

The primary goal of logging is to ensure that if your PL/SQL block has performance problems once deployed to production you should be able to identify the exact SQL or other PL/SQL component (eg a loop) that is causing the issue.

HINTS should be used to parallelise an operation if the operation is FULL TABLE SCAN ?

If parallelism is used in a DML then PX COORDINATOR should be below DML operation in the EXPLAIN PLAN ?

BITMAP INDEX is used in situations where the index is created after the table or partition is populated ?

As per BT security guide lines, account sharing is legal ?

Reading and writing data in datawarehouse should be maximized ?

In case of any deployment you if we need to backup data anywhere there must be a clear plan to remove this later. ?

For creating a table named T1 do we need to check whether that table exist or not ?

Business Logic comments is required for any SQL