Using the lookup cache
The Lookup Transformation can use two different connection types: the OLE DB connection, which requires the reference data to be stored in a data store that can be accessed by the OLE DB data provider, or a Cache connection that requires thee data to be available in an SSIS cache object.
In essence, there are three different modes of operation (depending on how the reference data is made available):
- In full cache mode, the reference data needs to be loaded completely into memory (cached) before the transformation can be used. Data is either loaded automatically (when an OLE DB connection is used to retrieve the lookup set), or needs to be loaded before the data flow, in which the lookup set is needed, and starts executing (when the cache connection is used to access the reference set).
- With partial cache, the reference data is loaded into memory at run time, while the pipeline rows are being processed, and the execution engine determines automatically (based on the reference...
