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

Informatica FAQ's part-9

116. Can you start batches with in a batch?

You cannot. If you wants to start batch that resides in a batch, create a new independent batch and copy the necessary sessions into the new batch.

117. Can you generate reports in Informatica?

Yes. By using Metadata reporter we can generate reports in Informatica.

118. Can you copy the batches?

No.

119. After dragging the ports of there sources(sql server, oracle, Infomix) to a single source qualifier, can you map these three ports directly to target?

No, Unless and until you join those three ports I source qualifier you cannot map them directly.

120. What are Target Types on the Server?

Target Types are File, Relational and ERP.

121.What is the aggregate transformations?

Aggregate transformation allows you to perform aggregate calculations, such as averages and sums.

122. What are Target Options on the Servers?

Target Options for File Target type are FTP File, Loader and MQ There are no target options for ERP target type.

123. How do you identify existing rows of data in the target table using lookup transformation?

Can identify existing rows of data using Unconnected transformation.

124. What is Code Page used for?

Code page is used to identify characters that might be I different languages. If your are importing Japanese data into mapping, you must select the Japanese code page of source data.

125. What is a source qualifier?

It represents all data queried from the source.

126. Where should you place the flat file to import the flat file definition to the designer?

Place it in Local folder.

127. What are the settings that you use to configure the joiner transformation?

1. Master and detail source
2. Type of join
3. Condition of the join

128. What are the session parameters?

Session parameters are like mapping parameters; represent values you might want to change between Sessions such as database connections or source files.

129. What are the methods for creating reusable transformations?

There are two methods:

1. Design it in the transformation developer.
2. Promote a standard transformation from mapping designer. After you ass a transformation to the mapping, you can promote it to the status of reusable transformation.

130. What are the joiner caches?

When a Joiner transformation occurs in a session, the Informatica Server reads all the records from the master source and builds index and data caches bases on the master rows. After building the caches, the Joiner transformation reads records from the detail source and performs joins.

131. What are different options uses to configure the sequential batches?

There are two options:

1. Run the session only if previous session completes successfully.
2. Always runs the session.

132. What are the data movement modes in Informatica?

Data movement modes determine how Informatica server handles the character data. You chooses the data movement in the Informatica server configuration settings Two types of data movement modes available in Informatica.

1. ASCII mode
2. Uni code mode

133. What is difference between stored procedure transformation and external procedure transformation?

Inner equi join.

134. What is difference between stored procedure will be compiled and external procedure transformation?

In case of stored procedure transformation procedure will be compiled and executed in a relational data source. You needs data base connection to import the stored procedure in to yours mapping. Where as in external procedure transformation procedure or function will be executed out side of data source. That is you need to make it as a DLL to access in your mapping. No need to have data base connection in case of external procedure transformation.

135. To achieve the session partition what are the necessary tasks you have to do?

1. Configure the session to partition source data.
2. Install the Informatica server on a machine with multiple CPU’S

source:www.dwhetltool.co.cc

Informatica FAQ's part-6

56. What is Forward Engineering?

Using the Erwin tool the data modeler will convert the .SQL script (logical structure of tables) into a physical structure tables at the database level, this is called as Forward Engineering.

57. What is common use of creating a Factless Fact Table?

The most common use of creating a Factless fact table is to capture date transaction events.

58. What are the different sources of Source systems of Data Warehouse?

1. RDBMS
2. Flat Files
3. XML Files
4. SAP R/3
5. PeopleSoft
6. SAP BW
7. Web Methods
8. Web Services
9. Seibel
10. Cobol Files
11. Legacy Systems.

59. You cannot use XML source qualifier in a mapplet and Joiner and Normalizer Transformations.

60. What are the Session Partitions types?

1. Round-robin
2. Hash keys
3. Key range
4. Pass-through
5. Database partitioning

61. You cannot use Incremental Aggregation when the mapping includes an aggregator transformation.

62.While importing source definition the metadata that will be imported are:

1. Source Name
2. Database Location
3. Column Names
4. Data Types
5. Key Constraints

63. We can stop the Batch by two ways:

1. Server Manager
2. By pmcmd command

64. What is stop the Batch and types of Batches?

Grouping of sessions is known as Batch. There are two types of batches:

1. Sequential
2. Concurrent

65. What is a tracing level and types of Tracing level?

Tracing level represents the amount of information that Informatica server writes in a log file. Types of Tracing levels are:

1. Normal
2. Verbose
3. Verbose lnit
4. Verbose Data

66. What is the default join that source qualifier provides?

Inner Join

67. Types of Slowly Changing Dimensions:

1. Type – 1 (Recent updates)
2. Type – 11 (Full historical information)
3. Type – 111 (Partial historical information)

68. What are Update Strategy’s target table options?

1. Update as Update: Updates each row flagged for update if it exists in the table.
2. Update as Insert: Inserts a new row for each update.
3. Update else Insert: Updates if row exists, else inserts.

69. What is a Data in a database this include the source of tables, the meaning of the keys and the relationship between the tables.

70. In Conceptual Modeling and Logical modeling the tables are called as entities.

71. What does a Mapping document contains?

The Mapping document contains the following information :

1. Source Definition – from where the database has to be loaded
2. Target Definition – to where the database has to be loaded
3. Business Logic – what logic has to be implemented in staging area.

 source:www.dwhetltool.co.cc

Informatica FAQ's part-8

96. Why we use partitioning the session in Informatica?

Partitioning achieves the session performance by reducing the time period of reading the source and loading the data into target.

97. Why we use lookup transformation?

Look up Transformations can access data from relational tables that are not sources in mapping. With Lookup transformation, we can accomplish the following tasks.

98. Which transformation should we use to normalize the COBOL and relational sources?

When you drag the COBOL source into the Designer workspace, the normalized transformation automatically appears, creating input and output ports for every column in the source.

99. Which tool you use to create and manage sessions and batches and to monitor and stop the Informatica server?

Informatica server manager.

100. What are the types of data that passes between Informatica server and stored procedure?

There are three types of data

1. Input/output parameter
2. Return Values
3. Status code

101. What are the groups available in Router Transformation?

1. User defined group
2. Default group

102. What are join types in Joiner Transformation?

The joins supplied by the Joiner Transformation are:

1. Normal Join
2. Master Outer Join
3. Detail Outer Join
4. Full Outer Join

103. What are the designer tools available for creation of Transformations?

1. Mapping Designer
2. Transformation Developer
3. Mapplet Designer

104. What are the basic needs to join two sources in Source Qualifier?

The two source tables should have a primary key – foreign key relationship and the two source tables should have matching data types.

105. What is a Status code?

Status code provides error handling facility during the session execution.

106. What is Data Driven?

The Data Driven is the instruction which is fed to Informatica Server whether to insert/delete/update when using Update Strategy Transformation.

107. What are the tasks to be done to partition a session?

• Configure the session to partition the source data
• Install the Informatica on a machine with multiple CPU

108. In which circumstances the Informatica creates a reject file (bad file)?

When it encounters the DD_REJECT in Update strategy Transformation

Voilets database constraints file in the rows was truncated or overflowed.

109.In a sequential batch can you run the session if previous session fails?

Yes, by setting the option always runs the session.

110. How many ways your create ports?

Two ways:

1. Drag the prot from another transformation
2. Click the add button on the ports tab.

111. How can you stop the batch?

By using server manager or pmcmd.

112.How can you improve session performance in aggregator transformation?

Use sorted input.

113. Can you use the mapping parameters or variables created in one mapping into any other reusable transformation?

Yes, because reusable transformation is not contained with any mapplet or mapping.

114. Can you use the mapping parameters or variables created in one mapping into another mapping?

No.

We can use mapping parameters or variables in any transformation of the same mapping or mapplet in which you have created mapping parameters or variables.

115. Can you start a session inside a batch individually?

We can start our required session only in case of sequential batch in case of concurrent batch. We can do like this.

source:www.dwhetltool.co.cc

Informatica FAQ's part-7

72. What does the Top Down Approach says?

The Top Down Approach is coined by Bill Immon. According to his approach he says “First we need to implement the Enterprise data warehouse by extracting the data from individual departments and from the Enterprise data warehouse develop subject oriented databases called as “Data Marts”.

73. What does the Bottom Up Approach or Ralph Kimball Approach says?

The Bottom Down Approach is coined by Ralph Kimball. According to his approach he says “First we need to develop subject oriented database called as “Data Marts” then integrate all the Data Marts to develop the Enterprise data warehouse.

74. Who is the first person in the organization to start the Data Warehouse project?

The first person to start the Data Warehouse project in a organization is Business Analyst.

75. What is a Dimension Modeling?

A Dimensional Modeling is a high level methodology used to implement the start schema structure which is done by the Data Modeler.

76. What are the types of OLAPs ?

1. DOLAP: The OLAP tool which words with desktop databases are called as DOLAP. Example: Cognos EP 7 Series and Business Objects, Micro strategy.
2. ROLAP: The OLAP which works with Relational databases are called as ROLAP. Example: Business Object, Micro strategy, Cognos ReportNet and BRIO.
3. MOLAP: The OLAP which is responsible for creating multidimensional structures called cubes are called as MOLAP. Example: Cognos ReportNet.
4. HOLAP: The OLAP which uses the combined features of ROLAP and MOLAP are called as HOLAP. Example Cognos ReportNet.

77. What is the extension of Repository backup?

The extension of the Repository backup is .rep

78. Which join is not supported by Joiner Transformation?

The non-equi joins are not supported by joiner Transformation.

79. What is SQL Override?

Applying the joining condition in the source qualifier is called as sql override.

80.What is Rank Index?

When you create a Rank Transformation by default “Rank Index” port will be created, to store the number of ranks specified.

81. What is Sort Key?

The column on which the sorting takes place in the Sorter Transformation is called as “Sort Key” Column.

82. What is default group in Router Transformation?

In the Router Transformation the rejected rows are captured by default group and the data will be passed to target table.

83. What is unconnected Transformation?

The transformation which does not involve in mapping data flow is called as Unconnected Transformation.

84. What is Connected Transformation?

The Transformation which involve in mapping data flow is called as connected transformation. By default all the transformation are connected transformation.

85. Which Transformation is responsible to maintain updates in warehouse database?

Update Strategy Transformation.

86. What are the caches contained by the Look up Transformation?

1.     Static Lookup cache

2.     Dynamic Lookup Cache

3.     Persistent Lookup Cache

4.     Data cache

5.     Index cache

87. What are the Direct and Indirect methods in the Flat file extraction?

In the direct method the extract the flat file by using its own meta data. In indirect method we extract all the flat files by using one flat file’s meta data.

88. What is the Maplet?

Mapplet is type of meta data object which contains set of reusable transformation logic which can be reused in multiple mapping. A maplet contains one maplet input Transformation and one maplet output Transformation.

89. What is the basic difference between reusable transformation and mapplet?

Maplets are set of reusable transformation logic and reusable transformations are created by single transformation logic.

90. What is Target Load Planer?

The Target Load plan is the order in which we should load the target to implement the Data Acquisition Process.

91.  What is Constraint Based Load ordering?

The Constraint Based Load ordering specified the loading of the dimensions tables based on the constraints designed in the dimension table. The Constraint Based Load order is used for implementing snow-flake schema data loading.

92. How may Loading criteria?

There are three types of Loading criteria.

1. Paralle loading
2. Sequential
3. Control flow loading

93. What is File Watch Event?

The Event Wait activity of a session has event called as File Watch which will watch wether the file is copied or not.

94. What is worklet?

The worklet is a group of sessions. To execute the worklet we have to create the workflow.

95. Why we use stored procedure transformation?

For populating and maintaining databases.

source:www.dwhetltool.co.cc