I/O operations on the data warehouse is expensive ?
True
False
SYS_CONTEXT can be used to know details about a session running the code?
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 ?