difference between lookup file set stage and file set stage

vbeeram · Post by **vbeeram** » Sun Jun 25, 2006 6:26 pm

I am reading Ascential manuals ,it is mentioned like lookup file set stage and file set stage will crete file with extension .fs.
What is the difference between two stages?

thanks in advance
Beeram

bmadhav · Post by **bmadhav** » Sun Jun 25, 2006 7:45 pm

This topic has been discussed a lot before.
Look at this blog link posted by Vincent, it shd help u:

http://blogs.ittoolbox.com/bi/websphere ... types-7183

kumar_s · Post by **kumar_s** » Mon Jun 26, 2006 12:29 am

Try to search the forum for Datset, fileset, Lookup fileset.
All the three files are created by datastage and for datastage.
All these files will have a descriptor file this is the contro file, which gives you the information where the actual data file resides.
Based on your config file (.apt) the number of nodes and hence the number of data file part is decided.
Dataset's data file part is in the format where it can be read only by datastage.
And so lookup file set. In addition, it will be internally indexed based on the the key mentioned. This is to ensure the max performance during lookup.
Fileset will store the data files in ASCII format. Which might also helps you to make any backup.
Both Fileset and Lookup file set will have the extension as .fs but Lookup fileset is one tuned for lookup.

ray.wurlod · Post by **ray.wurlod** » Mon Jun 26, 2006 12:34 am

A File Set is a number of data files, in human-readable format, spread over the specified processing nodes. It does not require a key column to be specified in its record schema.

A Lookup File Set has a similar physical structure, but does require a key column to be specified. Or more than one. This information in the schema is used to construct an index through which specific records can be accessed quickly.

For this reason, a File Set stage allows View Data but a Lookup File Set stage does not.