# 3i Infotech Papers: Sample Questions 174 - 175 of 1245

Examrace Placement Series prepares you for the toughest placement exams to top companies.

## Question number: 174

Essay Question▾

### Describe in Detail

What is an Oracle Instance?

### Explanation

• All running Oracle database is related with an Oracle instance.

• Oracle allocates a memory area called the System Global when a database is started on a database server Area and starts one or more Oracle processes.

• Oracle instance is the combination of the SGA and the Oracle processes.

• An Oracle instance can access only one database at a time, while an Oracle database can be accessed by multiple instances.

• Oracle database-wide system memory is known as the SGA, the system global area or shared global area.

• The data and control structures in the SGA are shareable, and all the Oracle background processes and user processes can use them.

## Question number: 175

Essay Question▾

### Describe in Detail

What are the notations used in Evaluation of Arithmetic Expression using prefix and postfix forms?

### Explanation

• Polish and reverse polish are the notations used in evaluation of arithmetic expression using prefix and postfix forms.

## Polish notation:

• Polish notation is also called as prefix notation.

• A form of notation for logic, arithmetic, and algebra.

• Its distinguishing feature is that it places operators to the left of their operands.

• While prefixing the operator to the number, it is called polish notation.

For example, ( (a + B) *C (D E) ^ (F + G) )

Prefix notation: ^-*+ABC-DE + FG

## Reverse Polish notation:

• A mathematical notation where every operator follows all of its operands, in contrast to Polish notation, which puts the operator in the prefix position.

• It suffixes the operator to the number called reverse polish notation.

Ex. . ( (a + B) *C (D E) ^ (F + G) )

Postfix notation: AB + C*DE—FG+^