Basically source qualifier is a representation of the records that Informatica server reads when it runs the session. It is associated with a source can be a table or flat file as well.
It is capable of doing a
filtration of records based on the condition we provide in the SQL override.
We can have a number of tables (from homogenous sources) joined inside the
SQL override of a source qualifier.
It is used in the very early stage of the mapping.
Filter is a transformation that is used after source qualifier (even if it is brought at the earliest in the mapping).
It can filter out records based on a condition we provide.
We should try to reduce the number of records into the mapping by filtering them out in the source qualifier itself.
We should try to use a filter only when there is no way out.
As a practice we should use as less transformation as possible.
By using Source Qualifier we can filter out records from only relational sources. But by using Filter Transformation we can filter out records from any sources.
In Filter Transformation we can use any expression to prepare filter condition which evaluates to TRUE or FALSE. The same cannot be done using Source Qualifier.
In Source Qualifier we can filter records from different source systems(Relational or Flatfile). In Filter Transformation we will filter those records which we need to update or proceed further. In simple before Filter Transformation the data from source system may or may not be processed(ExpressionTransformation, etc...).
The main difference between Source qualifier and Filter is In source qualifier you can have different database\'s sources but in filter you need same databases\'s source.And for performing tunning better you use source qualifier instead of filter.
Source Qualifier Transformation:
1. Source Qualifier transformation filters rows when read from a source.
2. Source Qualifier transformation can only filter rows from Relational Sources.
3. Source Qualifier limits the row set extracted from a source.
4. Source Qualifier reduces the number of rows used throughout the mapping and hence it provides better performance.
5. The filter condition in the Source Qualifier transformation only uses standard SQL as it runs in the database.
1.Filter transformation filters rows from within a mapping
2. Filter transformation filters rows coming from any type of source system in the mapping level.
3. Filter transformation limits the row set sent to a target.
4. To maximize session performance, include the Filter transformation as close to the sources in the mapping as possible to filter out unwanted data early in the flow of data from sources to targets.
5. Filter Transformation can define a condition using any statement or transformation function that returns either a TRUE or FALSE value.