Saturday, 1 September 2012

Types of Lookup Transformations

1. Connected or Unconnected:
They differ in the way output is received. In Connected Lookup the input is received through pipeline whereas in Unconnected Lookup receives input values from the result of a :LKP expression in another transformation
2. Lookup via Flat File or Relational:
After creating Lookup Transformation we can lookup either on a Flat file or on relational tables.
When we do Lookup on Relational tables we have to connect to the required table which will be there in the source list of Lookup. If it’s not there then we need to import the table definition for the Lookup Transformation
When we do Lookup on Flat files the Designer invokes the Flat File Wizard and connects the source.
3. Cached or Uncached :
Lookup Cache can be of two types:
1. Dynamic Cache: If its Dynamic Cache then integration service takes the rows from the cache .This improves the session performance and speeds up the activity.
2. Static Cache: By default the Lookup cache will be static and will not change during the entire session.

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