What are Dimensions and various types of Dimensions?

 set of level properties that describe a specific aspect of a business, used for analyzing the factual measures of one or more cubes, which use that dimension. Egs. Geography, time, customer and product.

Dimensions are classified to 3 types.

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

2.SCD TYPE 2(Slowly Changing Dimension): which contains current data,+complete  historical data.

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


What is Data Transformation Manager?

After the load manager performs validations for the session, it creates the DTM process. The DTM process is the second process associated with the session run. The primary purpose of the DTM process is to create and manage threads that carry out the session tasks.

 The DTM allocates process memory for the session and divide it into buffers. This is also known as buffer memory. It creates the main thread, which is called the master thread. The master thread creates and manages all other threads.

· If we partition a session, the DTM creates a set of threads for each partition to allow concurrent processing.. When Informatica server writes messages to the session log it includes thread type and thread ID.

Following are the types of threads that DTM creates:
Master Thread – Main thread of the DTM process. Creates and manages all other threads.
Mapping Thread – One Thread to Each Session. Fetches Session and Mapping Information.
Pre and Post Session Thread – One Thread each to Perform Pre and Post Session Operations.
Reader Thread – One Thread for Each Partition for Each Source Pipeline.
Writer Thread – One Thread for Each Partition if target exist in the source pipeline write to the target.
Transformation Thread – One or More Transformation Thread For Each Partition.


What is Session and Batches?

Session – A Session Is A set of instructions that tells the Informatica Server How And When To Move Data From Sources To Targets. After creating the session, we can use either the server manager or the command line program pmcmd to start or stop the session.Batches – It Provides A Way to Group Sessions For Either Serial Or Parallel Execution By The Informatica Server. There Are Two Types Of Batches :

Sequential – Run Session One after the Other.concurrent – Run Session At The Same Time.