Derived Column Transform limitations?

  • Is there a limit to how many functions you can use at once for a single derived column? For example i am trying to us the following... (DT_I4)SUBSTRING([Column 0],57,65) as a new column. The source is a fixed length string pulled out of a flat file. It redirects my output to the error output as set up. I get an errorcode -1073442796 "An error occurred during the computation of the expression." There are a couple of small square boxes at the tail end of that last statement that it won't let me cut and paste which I think probably represent either a LF or CR. These are at the end of each row which is about 1500 characters long. Is it a limitation to the Expression column on doing a function and cast at the same time?

  • There is some limit. I don't think it is the number of nested functions, I think it is the length of the text of the expression. It's pretty long though. I have had to split up some expressions into two derived column components to get around it, but the expressions were really complicated (hundreds of characters nested several times).

    The error you are getting is not one I have seen before. I would guess it is in the SUBSTRING. Possibly it hit a row that has less characters than your start position? Try just the SUBSTRING to make sure you do not error and get valid integer values for the conversion. The conversion should indicate a type cast issue if that is the problem, but SSIS errors are sometimes a little inconsistent.

  • I tried putting two Derived Column objects in line with the substring function in the first and the cast in the second and it works fine without any errors. The derived value in the second Derived Column object shows up as a valid 9 digit integer so the substring is isolating integers only as it should. I am not really seeing any short rows because my rowcount is consistantly the same all the way across the data flow.

  • It was the substring length that was the problem. I had the wrong lengths and it was masked by the fact these are fixed length rows with a lot of spaces between the columns of data. Thansk for the help. You definately got me looking in the right place.

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