By default, the Integration Service shares the cache for Lookup transformations in a mapping that have compatible caching structures. For example, if a mapping contains two instances of the same reusable Lookup transformation in one mapping and you use the same output ports for both instances, the Lookup transformations share the lookup cache by default.

The Integration Service builds the cache when it processes the first Lookup transformation. It uses the same cache to process subsequent Lookup transformations that share the cache. When the Integration Service shares a lookup cache, it writes a message in the Integration Service log.

The Integration Service allocates data cache memory and index cache memory for the first Lookup transformation. It does not allocate additional memory for subsequent Lookup transformations that share the lookup cache.

If the transformation or the cache structure do not allow sharing, the Integration Service creates a new cache.