Set - 1

Question 46 :

What does a Control file Contain ?

Answer :

A Control file records the physical structure of the database. It contains the following information.
Database Name
Names and locations of a database's files and redolog files.
Time stamp of database creation.

Question 47 :

What is difference between UNIQUE constraint and PRIMARY KEY constraint ?

Answer :

A column defined as UNIQUE can contain Nulls while a column defined as PRIMARY KEY can't contain Nulls.

Question 48 :

What is Index Cluster ?

Answer :

A Cluster with an index on the Cluster Key

Question 49 :

When does a Transaction end ?

Answer :

When it is committed or Rollbacked.

Question 50 :

What is the effect of setting the value "ALL_ROWS" for OPTIMIZER_GOAL parameter of the ALTER SESSION command ? What are the factors that affect OPTIMIZER in choosing an Optimization approach ?

Answer :

The OPTIMIZER_MODE initialization parameter Statistics in the Data Dictionary the OPTIMIZER_GOAL parameter of the ALTER SESSION command hints in the statement.