Error while using Transforms RowProcCompareWithPreviousValue

asvictor · Post by **asvictor** » Wed Nov 19, 2003 11:30 pm

HI,

I was trying to use RowProcCompareWithPreviousValue and am getting wrong results it always returns 1 as a return value even if there is a difference in the Value. Is there any restriction in using this Transforms. Do I need to use only String as datatype or use only tables to compare?
I tried to take a Seq File and sort it and Compare the Previous value and assigning a running no for the Records.

Cheers

ray.wurlod · Post by **ray.wurlod** » Thu Nov 20, 2003 12:36 am

Have you read the caveat in the long description of the Transform? In particular, are you using the same Transform more than once in the same process-chain in the job?

You may find it easier/better to use a pair of stage variables in a Transfomer stage to detect change; and this approach does not use COMMON, one of the contraindicators for using row buffering.

Variables might be called varHasChanged and varPrevValue. The varHasChanged variable is declared earlier than varPrevValue. varHasChanged is initialized to @FALSE, varPrevValue is initialized to anything you like. Derivation expressions are:

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varHasChanged:  InLink.colname <> varPrevValue AND @INROWNUM > 1
varPrevValue:   InLink.colname

Of course, this approach relies upon the input stream being sorted by values of colname.

kduke · Post by **kduke** » Thu Nov 20, 2003 12:46 am

Ray is correct. The compare routine uses @USER variables to store values which do not work if you call it more than once or have multiple transforms. Stage variables are far more reliable.

Kim.

thurmy34 · Post by **thurmy34** » Fri Mar 13, 2009 4:16 am

Hi all,
Maybe should i create a new topic but i want to let you what i found with RowProcCompareWithPreviousValue.

I use it to eliminate duplicate records in a transformer.
The strange thing is that sometimes i had false duplicate.

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ex 
   330285131|20081130 
   330285131|20081230 --> 0
   330285131|20081231 --> 1 (witch it's wrong).

I changed to the two variables way but the results was the same.
I resolved the problem by changing the order of the "key"

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ex 
   20081130|330285131
   20081230|330285131 --> 0
   20081231|330285131 --> 0 (ok now).

chulett · Post by **chulett** » Fri Mar 13, 2009 7:28 am

So... do you actually have a question or is this just an informational post?

thurmy34 · Post by **thurmy34** » Fri Mar 13, 2009 7:39 am

It's just informational like a How to.

chulett · Post by **chulett** » Fri Mar 13, 2009 8:14 am

That's

just wanted to be sure we didn't leave you hanging.

thurmy34 · Post by **thurmy34** » Fri Mar 13, 2009 8:16 am

I appreciate