I am using SSIS to export data from an Oracle database. Sometimes when I export a VARCHAR2 column to NVARCHAR the last character gets truncated (silently). It's completely random as far as I can tell. I have tried using different SSIS data types (DT_STR, DT_WSTR and DT_NTEXT) but the problem persists. The source string is always 12 characters long ([0-9A-Z] only), but when I check the destination database some columns are missing the last character.

I use the latest 32bit Oracle Instant Client (11.2) with ODBC and SQL Server 2008 R2. I use ADO .NET for both source and destination. The source character set is AMERICAN_AMERICA.WE8ISO8859P1 and the source and destination columns are declared as VARCHAR2 (12 BYTES) and NVARCHAR(12) respectively.

  • Try: select length(to_nchar(source_column)), count(*) from source_table group by length(to_nchar(source_column)); and see if you'll get any truncation due to VARCHAR->NVARCHAR issues
    – Philᵀᴹ
    Apr 2, 2012 at 22:54
  • I ran the query and all columns are 12 characters. No truncation.
    – josjo
    Apr 3, 2012 at 6:56
  • I just want to clarify that the truncation happens in a random pattern. Different rows gets truncated on every export and sometimes there is no truncation at all.
    – josjo
    Apr 3, 2012 at 6:59
  • Just want to mention I typoed the above query. length() should have been lengthb() (for length in bytes, rather than length in characters).
    – Philᵀᴹ
    Apr 3, 2012 at 8:22
  • With lengthb() i get exactly double the length for all rows (24 bytes).
    – josjo
    Apr 3, 2012 at 8:30

1 Answer 1


It looks like the problem was caused by a data flow task where I had two different data flows running in parallel. The same source tables were involved in both data sources but with different destinations. When I broke the task up into two tasks running one after the other, the truncation problem seems to have gone away.


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