testguide_1635

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Name of Solution:

Mapping: Incremental Extraction of Source

Business Requirement:

Informatica PowerCenter mapping to automate the incremental extraction of source rows

using Mapping Variable functionality.

Solution URL:

https://community.informatica.com/solutions/1635

Supported Version:

PowerCenter 9.1 and 9.5

Description:

When data in a source table is frequently updated, it is necessary to capture the updated

information in the data warehouse. However, due to data volumes and load window

considerations, it is desirable to process only those records that have been updated, rather

than re-reading the entire source into a mapping.

Usually there is an update timestamp column in the source table. This column can be used

to filter the source records for reading the updated rows. This filter condition has to change

every time the mapping is run to extract only the records that were updated since the last

run. This mapping template illustrates a method of using the mapping parameter

functionality to dynamically build the filter every time the mapping run.

The mapping in this template uses a mapping parameter file, which stores the parameter

value to track and store the maximum value of update timestamp every time the session

runs. For the first run a mapping parameter file is, it can be called by mapping logic at

runtime from the second run.

When a session begins, it takes the default value of the mapping parameter for the first run

and from the second run value is taken from parameter file. When the session ends, it saves

the new value of the mapping parameter back to the parameter file, to be used the next

time the session is run.

Download file contents:

1. Workflow

2. Scripts


Pre-Requisites / System Requirement:

1. Scripts for table structure and data are provided with bundle. Scripts can be found in

Scripts folder after extract.

2. UpdateData script needs to be implemented for second execution.

3. Observe the mapping objects and check for initial value of mapping parameter.

Steps to implement the solution:

1. Execute the Scripts\LoadData.Sql the database. This should create source and

target table with data. Observe the data of source and target as per following

screenshots respectively.

2. Import wf_m_Extract_Incremental_Changes.xml using Repository Manager.

Note: The core functionality of this solution is present as a mapplet in

wf_m_Extract_Incremental_Changes_With_Mapplet.XML. If you want to use this

solution as a mapplet in any of your mappings, just copy the mapplet after importing

the contents export file.

3. Select the appropriate folder from repository and resolve the conflicts by choosing

suitable option.

4. Open the workflow wf_m_Extract_Incremental_Changes.xml in Workflow Manager.

5. Assign the integration service in Workflow -> Edit -> Integration Service.

6. Edit session and assign valid connection object for the source and target.

7. For more details for importing object please visit our YouTube link.


8. Run the workflow and observe the result Workflow Monitor. Only four rows are

considered for update since only those satisfy the condition. Observe the data in

database.

9. Execute Scripts\UpdateData.Sql in the database. Observe that first three rows are

updated. Have a look at time stamp column.

10. For the second run, edit workflow and paste the parameter file path as shown below.

11. Execute the workflow and observe the result in Workflow Monitor. Observe that only

two rows are getting updated.

YouTube Video on Importing and Configuring Workflows:

http://www.youtube.com/playlist?list=PLLRreK2jjjgWBQ4NPfp0QWTxYDvlnEqSJ

Other Useful links:

Mapping Bundles

Workflow Bundles

Informatica Tools Bundles

Informatica for Social Media Bundles

Debugging Tools Bundles

Visio Templates Bundles

B2B Templates and Projects Bundles

Data Quality Packs and Plans Bundles

Script Bundles

Documents

testguide_1635