The Source Qualifier transformation represents the rows that the PowerCenter Server reads when it runs a
session.
It is only transformation that is not reusable. And it is the default transformation except in case of XML or COBOL files.
Tasks to performed by Source Qualifier:
- Join data originating from the same source database: We can join two or more tables with primary key-foreign key relationships by linking the sources to one Source Qualifier transformation.
- Filter rows when the PowerCenter Server reads source data: If we include a filter condition, the PowerCenter Server adds a WHERE clause to the default query.
- Specify an outer join rather than the default inner join: If we include a user-defined join, the PowerCenter Server replaces the join information specified by the metadata in the SQL query.
- Specify sorted ports: If we specify a number for sorted ports, the PowerCenter Server adds an ORDER BY clause to the default SQL query.
- Select only distinct values from the source: If we choose Select Distinct, the PowerCenter Server adds a SELECT DISTINCT statement to the default SQL query.
- Create a custom query to issue a special SELECT statement for the PowerCenter Server to read source data: For example, you might use a custom query to perform aggregate calculations.
