Derived column truncation error

Question

Derived column truncation error

Ali Ahad 151

I am getting following truncation error message in the derived column transformation:

The "Derived Column" failed because truncation occurred, and the truncation row disposition on "Derived Column.Outputs[Derived Column Output].Columns[DESCRIPTION]" specifies failure on truncation. A truncation error occurred on the specified object of the specified component.

[SSIS.Pipeline] Error: SSIS Error Code DTS_E_PROCESSINPUTFAILED. The ProcessInput method on component "Derived Column" (56) failed with error code 0xC020902A while processing input "Derived Column Input" (57). The identified component returned an error from the ProcessInput method. The error is specific to the component, but the error is fatal and will cause the Data Flow task to stop running. There may be error messages posted before this with more information about the failure.

I am using the following expression for the derived column

(DT_STR,8000,1252)(DT_TEXT,1252)[Description]

Screenshot 2026-06-02 224811

Any help would be appreciated.

Thanks,

Ali.

Deepesh Dhake 80 Reputation points

2026-06-04T03:50:16.0833333+00:00
For large LOB data, the reliable options are:

Keep full text (recommended) : replace the expression with:

(DT_TEXT,1252)[Description]

The output column becomes DT_TEXT. Map it to a varchar(max)/text destination.

Allow silent truncation to 8000 chars : keep your current expression, then open the Advanced Editor then Input/Output Properties then Derived Column Output then Columns then DESCRIPTION then set TruncationRowDisposition to RD_IgnoreFailure. Truncates at 8000 bytes (= 8000 chars under codepage 1252). Use only if data loss is acceptable.

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Deepesh Dhake 80 Reputation points

2026-06-04T03:50:16.0833333+00:00

For large LOB data, the reliable options are:

Keep full text (recommended) : replace the expression with:

(DT_TEXT,1252)[Description]

The output column becomes DT_TEXT. Map it to a varchar(max)/text destination.

Allow silent truncation to 8000 chars : keep your current expression, then open the Advanced Editor then Input/Output Properties then Derived Column Output then Columns then DESCRIPTION then set TruncationRowDisposition to RD_IgnoreFailure. Truncates at 8000 bytes (= 8000 chars under codepage 1252). Use only if data loss is acceptable.

Answer 1

The error occurs because the Derived Column is configured to fail on truncation and the cast from DT_TEXT to DT_STR,8000 is truncating some rows.

In SSIS, truncation is treated separately from hard errors. When a truncation happens and the column’s TruncationRowDisposition is set to Fail Component, SSIS raises DTS_E_INDUCEDTRANSFORMFAILUREONTRUNCATION (0xC020902A) and stops the Data Flow.

To resolve this, use one of these options:

Increase or change the data type
- If the destination can store longer text, avoid truncation by:
  - Using a Unicode/text type at the destination (e.g., DT_TEXT/NTEXT equivalent) instead of DT_STR(8000).
  - Or increasing the length of the target column so it can hold the maximum length of [Description].
Allow truncation but keep the row
- In the Derived Column editor, open the Configure Error Output dialog for the Derived Column component.
- For DESCRIPTION, set Truncation to Ignore failure.
- This keeps the row and silently truncates the value to 8000 characters.
Redirect truncated rows for inspection
- In Configure Error Output, set Truncation to Redirect row for DESCRIPTION.
- Connect the error output to another destination (e.g., a table or flat file) to capture rows where truncation occurs and review them.

These behaviors (Fail Component, Ignore Failure, Redirect Row) are the standard SSIS options for handling truncations and are what control whether the Derived Column fails when truncation happens.

References:

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Derived column truncation error

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