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