Informatica Interview Questions and Answers

Q. What is the difference between $ & $$ in mapping or

parameter file? In which cases they are generally used?

A. $ prefixes are used to denote session Parameter and

variables and $$ prefixes are used to denote mapping parameters

and variables

Q. What are Target Types on the Server?

A. Target Types are File, Relational and ERP.

Q. What are Target Types on the Server?

A. Target Types are File, Relational and ERP.

Q. How do you identify existing rows of data in the target table

using lookup transformation?

A. There are two ways to lookup the target table to verify a row exists

or not :

1. Use connect dynamic cache lookup and then check the values of

NewLookuprow Output port to decide whether the incoming record

already exists in the table / cache or not.

2. Use Unconnected lookup and call it from an expression

transformation and check the Lookup condition port value (Null/ Not

Null) to decide whether the incoming record already exists in the table

or not.

Q. What are Aggregate transformations?

A. Aggregator transform is much like the Group by clause in traditional

SQL.

This particular transform is a connected/active transform which can

take the incoming data from the mapping pipeline and group them

based on the group by ports specified and can caculated aggregate

functions like ( avg, sum, count, stddev....etc) for each of those groups.

From a performance perspective if your mapping has an AGGREGATOR

transform use filters and sorters very early in the pipeline if there is

any need for them.

Q. What are various types of Aggregation?

A. Various types of aggregation are SUM, AVG, COUNT, MAX, MIN,

FIRST, LAST, MEDIAN, PERCENTILE, STDDEV, and VARIANCE.

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Q. What are Dimensions and various types of Dimension?

A. Dimensions are classified to 3 types.

1. SCD TYPE 1(Slowly Changing Dimension): this contains current

data.

2. SCD TYPE 2(Slowly Changing Dimension): this contains current

data + complete historical data.

3. SCD TYPE 3(Slowly Changing Dimension): this contains current

data.

Q. What are 2 modes of data movement in Informatica Server?

A. The data movement mode depends on whether Informatica Server

should process single byte or multi-byte character data. This mode

selection can affect the enforcement of code page relationships and

code page validation in the Informatica Client and Server.

a) Unicode - IS allows 2 bytes for each character and uses additional

byte for each non-ascii character (such as Japanese characters)

b) ASCII - IS holds all data in a single byte

The IS data movement mode can be changed in the Informatica Server

configuration parameters. This comes into effect once you restart the

Informatica Server.


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Q. What is Code Page Compatibility?

A. Compatibility between code pages is used for accurate data

movement when the Informatica Sever runs in the Unicode data

movement mode. If the code pages are identical, then there will not be

any data loss. One code page can be a subset or superset of another.

For accurate data movement, the target code page must be a superset

of the source code page.

Superset - A code page is a superset of another code page when it

contains the character encoded in the other code page, it also contains

additional characters not contained in the other code page.

Subset - A code page is a subset of another code page when all

characters in the code page are encoded in the other code page.

What is Code Page used for?

Code Page is used to identify characters that might be in different

languages. If you are importing Japanese data into mapping, u must

select the Japanese code page of source data.

Q. What is Router transformation?

A. It is different from filter transformation in that we can specify

multiple conditions and route the data to multiple targets depending

on the condition.