Informatica FAQ's part-10

136. Performance tuning in Informatica?

The goal of performance tuning is optimize session performance so sessions run during the available load window for the Informatica server.

137.When can session fail?

The session fails when,

• Server cannot allocate enough system resources
• Session exceeds the maximum no. of sessions
• Server cannot obtain an execute lock for the session
• Server encounters database errors
• Network related errors

138. How many ways you can update a relational source definition?

There are ways you can update a relational source definition:

1. Edit the definition
2. reimport the definition

139. How many ways you can create a Reusable Transformation?

There are two ways to create a Reusable Transformation

1. By designing it in the transformation developer
2. By promoting the already existing Transformation to reusable from its properties.

140. What is a aggregator cache in aggregate transformation?

The aggregator transformation stores the data in the aggregator cache until it completes aggregate calculations.

141. What is data cache and Index cache?

When you use aggregator transformation in your mapping then Informatica server creates Data and Index cache in memory to process the transformation.

142. What is a Mapping Variable?

A Mapping Variable represents a value that can change throughout the session. The Informatica server saves the value of mapping variable in repository in the send of the session and uses it for the next session run.

143. In which scenario does the Update Strategy Transformation is best suited?

Within a session: When you configure a session, you can instruct the Informatica server to either treat all records in same way (treat all as insert/treat all as update/treat all as update) or use instructions coded into the session to flag records for different database operations.

Within a Mapping: Within a mapping, you use the update strategy transformation to flag records for insert, update or reject.

144. What are the types of mappings in Getting Started Wizard?

1. Simple pass through mapping: loads a slowly growing fact or dimension table be inserting new rows. Use this map to loading new data into it.
2. Slowly growing target: Loads a slowly growing fact or dimension table be inserting new rows. Use this map to load new data without disturbing the existing data.

145. How can you recognize whether or not the data is added in the table in Type – II dimension?

1. By version number
2. By flag value
3. By effective date range

146. Why you use Repository connectivity?

When you edit or schedule the session each time, Informatica server directly communicates the repository to check whether or not the session and users are valid.

147. What are the data movement modes in Informatica?

The data movement modes determines how Informatica server handles the character data. There are two types of data movement modes:

1. ASCII mode
2. Uni code mode

148. Can you copy the session to a different folder or Repository?

Yes. By using the copy session wizard you can copy a session in a different folder or Repository. But first you should copy the mapping of that session before you copy session.

149. What is the difference between partitioning of relational target and partitioning of file target?

If you partition a session with a relational target Informatica server creates multiple connections to the target database to write target data concurrently. If you partition a session with file target the Informatica server create one target file for each partition.

150. What are the Transformations that restrict the partition of sessions?

1. Advanced External Transformation
2. External Procedure Transformation
3. Aggregator Transformation
4. Joiner Transformation
5. Normalizer Transformation
6. XML Targets

151. What is a Power Center Repository?

The Power Center Repository allows you to share metadata across repositories to create a data mart domain. In a data mart domain, you can create a single global repository to store metadata used across an enterprise and a number of local repositories to share the global metadata as needed.

source:www.dwhetltool.co.cc