In Informatica Lookup transformation we have the option to the cache the Lookup table(Cached Lookup).If we don’t use the lookup cache its is called as Uncached Lookup.
In Uncached lookup we do lookup on the base table and will return output values based on the Lookup condition. If the lookup condition is matching it returns the value from Lookup table or cache .And if lookup condition is not satisfied then it returns either NULL or default value. This is how Uncached Lookup works
Now we will see what a Cached Lookup is!
In Cached lookup the Integration Service creates a Cache whenever the first row in the Lookup is processed. Once a Cache is created the Integration Service always queries the Cache instead of the Lookup Table. This saves a lot of time.
Lookup Cache can be of different types like Dynamic Cache and Static Cache
What is a Static Cache?
Integration service creates Static Cache by default while creating lookup cache. In Static Cache the Integration Service does not update the cache while it processes the transformation. This is why it’s called as Static.
Static Cache is same as a Cached Lookup in which once a Cache is created the Integration Service always queries the Cache instead of the Lookup Table.
In Static Cache when the Lookup condition is true it return value from lookup table else returns Null or Default value.
In Static Cache the important thing is that you cannot insert or update the cache.
What is a Dynamic Cache?
In Dynamic Cache we can insert or update rows in the cache when we pass the rows. The Integration Service dynamically inserts or updates data in the lookup cache and passes the data to the target. The dynamic cache is synchronized with the target.
Will discuss in detail about dynamic cache in upcoming posts