GUID/RAW stored in oracle match almost, except for last 4 characters

Question

We have noticed some strange behavior in our production data concerning the GUIDs we are storing from a .Net DataSet into an Oracle RAW column.

We have the following set up:

• Table A has a RAW column Id
• Table B has an RAW column ResponsibleObjectId

The ResponsibleObjectId column is filled with the ID of table A when it is created in function of Table A (not always the case, so there is no FK on the column).

This happens in our .Net server layer. The two tables are in 2 separate DataSets. These 2 datasets are then saved to an oracle DB (11g).

Most of the times this works, but in a few cases (like 1/10.000.000 rows) the resulting guids are not entirely the same:

ResponsibleObjectId                 ID
665B8FFDE5A04163A96D96A25702665B    665B8FFDE5A04163A96D96A257023065
325C8AB000434503B8D2F980B33B325C    325C8AB000434503B8D2F980B33B4B58
AF831B5207E04D2ABE0E3ADAC802AF83    AF831B5207E04D2ABE0E3ADAC8023FA1
88DD5AF244DC4EA08075DB53CA1988DD    88DD5AF244DC4EA08075DB53CA19072E
75A5E5111DEE4021BA6EB016178775A5    75A5E5111DEE4021BA6EB01617876E66

They match, expect for the last 4 characters.

We save the GUIDs using a stored procedure as follows:

.Net DAL

OracleCommand cmdSpInsert = (OracleCommand)database.GetStoredProcCommand("PKG_TableB.InsertTableB");
database.AddInParameter(cmdSpInsert, "PAR_ResponsibleObjectId", DbType.StringFixedLength, 36, "ResponsibleObjectId", DataRowVersion.Current);

Oracle SP

PROCEDURE InsertTableB
(
    ...
    PAR_ResponsibleObjectId IN CHAR,
    ...
)
IS BEGIN
    INSERT INTO StockMov
           (
                ...
                HEXTORAW(REPLACE(UPPER(PAR_ResponsibleObjectId), '-','')),
                ...
           );
END InsertTableB;

We have no idea what is causing this strange behavior. We've seen it happen in one similar case on 2 different columns in our Table A as well, so it does not seem related specifically to table B.

If any extra information is needed, please ask and I'll update the question.

Any help is greatly appreciated in solving our mystery! :)

Edit As asked in the comments, the assignment of the ResponsibleObjectId column very simple, like this:

dataSetB.ResponsibleObjectId = dataSetA.Id

Also the two datasets are saved in the same transaction.

Answer 1

byte[] idGuid = Guid.NewGuid().ToByteArray();

dataSetA.Id = idGuid;

dataSetB.ResponsibleObjectId = idGuid;

/* don't do dataSetB.ResponsibleObjectId = dataSetA.Id

don't do any data type conversions - keep it binary/raw */