You can configure a Lookup transformation to cache the lookup file or table. The Integration Service builds a cache in memory when it processes the first row of data in a cached Lookup transformation. It allocates memory for the cache based on the amount you configure in the transformation or session properties. The Integration Service stores condition values in the index cache and output values in the data cache. The Integration Service queries the cache for each row that enters the transformation.
The Integration Service also creates cache files by default in the $PMCacheDir. If the data does not fit in the memory cache, the Integration Service stores the overflow values in the cache files. When the session completes, the Integration Service releases cache memory and deletes the cache files unless you configure the Lookup transformation to use a persistent cache.
When configuring a lookup cache, you can configure the following options:
Recache from lookup source
You can use a dynamic cache for relational or flat file lookups.