An inside view of LOOKUP FILE

The LOOKUP FILE component represents a particular set of lookup data and associates it with a search key and a DML record format. At graph runtime, the Co>Operating System uses this information to load the data from disk into memory. Then your graph’s transform components retrieve records from the memory-resident lookup data using lookup functions.

When to use a LOOKUP FILE

You use a LOOKUP FILE component instead of an INPUT FILE component when your graph needs to access a dataset repeatedly. Retrieving records from main memory is much quicker than retrieving them from disk, so LOOKUP FILE can make graph processing quicker and more efficient. However, you have to make sure that the amount of data associated with the LOOKUP FILE is small enough to be held in main memory.

Static loading only

The LOOKUP FILE component is for statically loaded data only. When you use a LOOKUP FILE, the Co>Operating System (Server) loads data into memory once, at the start of the graph phase. After that, the data in memory cannot be refreshed.

If you need to load lookup data dynamically, use a LOOKUP TEMPLATE component instead of a LOOKUP FILE.