Lookup Cache

Lookup Cache:

 The Integration Service builds 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 we configure in the transformation or session properties. The Integration Service stores condition values in the index cache and output values in the data cache.

Types of cache:

Persistent Cache:  It is a kind of caching mechanism in the informatica lookup transformation. It allows to, save the lookup transformation cache in a file. So, that, we can reuse the cache from the cache file, next time when the Integration Service process the lookup transformation. Simply Persistent cache is a reusable cache.

How to create Persistent Cache?

1.       Open lookup properties tab.

2.       Check Lookup cache persistent option and give the Lookup cache directory name

3.       In the Cache File Name Prefix option you can give a file name prefix. 

4.       If you give the file name prefix, then Integration Service will create five files in the cache directory as

5.       If you not give the file name prefix, then the Integration Service will create four files in the cache directory as

Static Cache.

It is the default cache in the Lookup transformation. It caches the lookup file or table and lookup values in the cache for each row that comes into the transformation. The Integration Service does not update the cache while it processes the Lookup transformation.

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

 When the Lookup condition in not true, the Integration Service returns either NULL or default values. For connected Lookup transformations, the Integration Service returns default values 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 we create multiple partitions in a pipeline that use a static cache, the Integration Service creates one memory cache for each cache partition and one disk cache for each transformation.