By default, the Integration Service creates a static lookup cache when you configure a Lookup transformation for caching. The Integration Service builds the cache when it processes the first lookup request. It queries the cache based on the lookup condition for each row that passes into the transformation. The Integration Service does not update the cache while it processes the transformation. The Integration Service processes an uncached lookup the same way it processes a cached lookup except that it queries the lookup source instead of building and querying the cache.

When the lookup condition is true, the Integration Service returns the values from the lookup source or cache. For connected Lookup transformations, the Integration Service returns the values represented by the lookup/output ports. For unconnected Lookup transformations, the Integration Service returns the value represented by the return port.

When the condition is not true, the Integration Service returns either NULL or default values. For connected Lookup transformations, the Integration Service returns the default value of the output port when the condition is not met. For unconnected Lookup transformations, the Integration Service returns NULL when the condition is not met.

When you create multiple partitions in a pipeline that use a static cache, the Integration Service creates one memory cache for each partition and one disk cache for each transformation.