Trying to figure out the issue
I tried to search on this topic, i didn't find a lot of informations but i think it is based on the OLEDB Connection string provided in the OLEDB Connection Manager.
Check the following Oracle documentation it may give you some insights:
In the link above, in the Distributed Transactions part, they mentioned that:
The DistribTX
attribute specifies whether sessions are enabled to enlist in distributed transactions. Valid values are 0
(disabled) and 1
(enabled). The default is 1 which indicates that sessions are enabled for distributed transaction enlistments.
Sessions enabled for distributed transaction enlistments cannot run statements that use the direct path load and parallel DML capabilities of the Oracle database. Such statements are executed as conventional path serial statements.
I am not sure if this could help, but it is not bad to give a try.
Oracle Attunity Connectors
Instead of using OLEDB Source to read from oracle, it is better to use Oracle Attunity Connectors for SSIS which guarantee higher performance than OLEDB Source:
Attunity's high speed connectors for Oracle and Teradata have been selected by Microsoft to be included with SQL Server Integration Services (SSIS).