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Information carried by a link

Posted: Mon Dec 12, 2005 3:40 am
by koolnitz
Hi,

I want to know what are the info which are carried by a link from one stage to the next?

In one of my jobs, I have a link from Transformer stage to a DB2/UDB API stage. DB2 stage is a target stage. Now when I replaced the existing DB2 stage with a new one, the link carried the Table name also. For example, my previous DB2 stage was pointing to a table "XYZ", now this new DB2 stage automatically pointing to the same table "XYZ". As far as I know, the links carry only the columns info (column names, derivation logic, datatypes,..) and NOT the Tablename. This is a property to be set in DB2 stage. May be I am going wrong as I don't have much experience on DS.

Can somebody explain me?

Thanks!

Posted: Mon Dec 12, 2005 5:24 am
by ArndW
If you used the canvas and added a new DB/2 stage and dragged the link across then the stage information will also be transferred over; this is different from the link information. If you were to drag your link to a dataset and then drag it back to the DB/2 stage your table and DB/2 connection information will have been lost.

Posted: Mon Dec 12, 2005 12:28 pm
by ameyvaidya
As a general rule:

All info entered in the stage Page are associated with and stored as a property of the stage.

All Info entered in the <input/Output>/<LinkName> pages are associated and stored as a property of the link.

Each link will store 2 such sets of properties. 1 at the input and 1 at the output (Try setting input properties of a link and then flipping it around so that it becomes to output link to that stage instead of the input. Then flip it around again).

As Arnd mentioned above,post-disconnection, a link will remember its previous set of properties until they are overridden by connecting it to another stage.

Posted: Tue Dec 13, 2005 3:14 am
by koolnitz
Thanks guys!!
The points are making sense to me.

Posted: Tue Dec 13, 2005 3:21 pm
by ray.wurlod
Under the covers the design information is stored as jobs, containers, stages and "pins".

A "pin" is a connection between a link and a stage. Every link in a complete job is represented by two pin records.

The analogy is from electronic circuit boards, where the links are drawn on the board and components (such as integrated circuit chips) are connected to the links via pins.