When you preview a dynamic target, the Developer tool does not refresh the schema definition. If there is a mismatch due to changes in the schema such as a configuration to get columns from the data source or to replace the target at run time, the data preview fails. Manually synchronize the Read or Write transformation. If you continue to get an error, run the mapping to see the results.

If the dynamic target is too small for the incoming data, the mapping fails with a message indicated that the value is too large for the column.

The data types in the target table might be different from the data types in the Write transformation. When the Data Integration Service runs the mapping, it might change data types between upstream transformations and the target table.