Chaining reference input links

freef1yer · Post by **freef1yer** » Wed Jun 23, 2004 10:27 am

Hi All

I have a job with two reference input links to one transformer. The first reference input link takes its key value from the stream input. The second reference input link takes its key value from the first input reference link.

The UI didn't allow me to drag and drop this arrangement, and now it is in place, the key derivation for the second input reference link is shown in red. However, the job appears to compile without any problems.

Does this mean that, although the UI doesn't support this kind of reference chain within a single transformer, the method is valid and works correctly? (Assuming the input links are correctly ordered, of course.)

Has anybody else tried to do this?

Thanks

Dave

chulett · Post by **chulett** » Wed Jun 23, 2004 10:35 am

Yes. It is frowned upon by some, but as long as you understand the link ordering requirements and don't mind a little red in your jobs, it does work.

I personally don't do this, but I know people that do. It's a good thing to drop an annotation about in the job so people don't think something is 'broken' when they open the Transformer.

kcbland · Post by **kcbland** » Wed Jun 23, 2004 11:09 am

Or, this undocumented functionality may be removed in a subsequent patch, minor, or major release without notification. Doing what you're doing is exploiting a non-enforced trap in the GUI, obviously the RED is meant to say you shouldn't be doing this. Were this functionality to change, you're jobs could break after an upgrade.

chulett · Post by **chulett** » Wed Jun 23, 2004 11:13 am

See... frowned upon.

kcbland · Post by **kcbland** » Wed Jun 23, 2004 11:17 am

Yes, but whhhhyyyyyy is it frowned upon. Sometimes my priorities are considered "chicken-littleish".

ray.wurlod · Post by **ray.wurlod** » Wed Jun 23, 2004 4:20 pm

Dunno. The "approved" method would be to do the two reference lookups in two consecutive Transformer stages, passing the results of the first along the link between the first and the second.

kduke · Post by **kduke** » Wed Jun 23, 2004 5:46 pm

Ken's method runs faster. You know what I mean Ray?

kcbland · Post by **kcbland** » Wed Jun 23, 2004 8:27 pm

Hey wait a minute, I DON'T use the technique because the GUI represents this as invalid and Ascential could close the door on this technique at their perogative.

I think the functionality SHOULD be there to do this (remove the half-hearted GUI attempts to block it, you can still type in the column derivation and it works, even though it's red). But, never exploit a bug or a loophole, because you never know when it will get "fixed". You'll be fixed alright.

kduke · Post by **kduke** » Wed Jun 23, 2004 9:04 pm

I still like this method better than another transform.