Source Qualifier in Informatica

When you add a relational or a flat file source definition to a mapping, you need to connect it to a Source Qualifier transformation. The Source Qualifier represents the records that the Informatica Server reads when it runs a session.

You can use the Source Qualifier to perform the following tasks:

a) Join data originating from the same source database

You can join two or more tables with primary-foreign key relationships by linking the sources to one Source Qualifier.

b) Filter records when the Informatica Server reads source data

If you include a filter condition, the Informatica Server adds a WHERE clause to the default query.

c) Specify an outer join rather than the default inner join

If you include a user-defined join, the Informatica Server replaces the join information specified by the metadata in the SQL query.

d) Specify sorted ports

If you specify a number for sorted ports, the Informatica Server adds an ORDER BY clause to the default SQL query.

e) Select only distinct values from the source

If you choose Select Distinct, the Informatica Server adds a SELECT DISTINCT statement to the default SQL query.

f) Create a custom query to issue a special SELECT statement for the Informatica Server to read source data

For example, you might use a custom query to perform aggregate calculations or execute a stored procedure.

5. Stored Procedure

A Stored Procedure transformation is an important tool for populating and maintaining databases. Database administrators create stored procedures to automate time-consuming tasks that are too complicated for standard SQL statements.

A stored procedure is a precompiled collection of Transact-SQL statements and optional flow control statements, similar to an executable script. Stored procedures are stored and run within the database. You can run a stored procedure with the EXECUTE SQL statement in a database client tool, just as you can run SQL statements. Unlike standard SQL, however, stored procedures allow user-defined variables, conditional statements, and other powerful programming features.

Not all databases support stored procedures, and database implementations vary widely on their syntax. You might use stored procedures to:

a) Drop and recreate indexes.

b) Check the status of a target database before moving records into it.

c) Determine if enough space exists in a database.

d) Perform a specialized calculation.

Database developers and programmers use stored procedures for various tasks within databases, since stored procedures allow greater flexibility than SQL statements. Stored procedures also provide error handling and logging necessary for mission critical tasks. Developers create stored procedures in the database using the client tools provided with the database.

The stored procedure must exist in the database before creating a Stored Procedure transformation, and the stored procedure can exist in a source, target, or any database with a valid connection to the Informatica Server.

You might use a stored procedure to perform a query or calculation that you would otherwise make part of a mapping. For example, if you already have a well-tested stored procedure for calculating sales tax, you can perform that calculation through the stored procedure instead of recreating the same calculation in an Expression transformation.