I am trying to track down a cause for a difference in oracle impdp processing, and I am not finding anything, so I am wondering if anyone here can explain the cause of the differences.
At times I have seen times where using the parallel=x parameter in oracle datapump will cause either multiple tables to be inserted at once, up to the value of 'x', or other times will use parallel threads to import a single table.
I have not been able to track down what might be causing the difference in performance, and I am wondering if anyone has an explanation, or even just a direction to point me to. It would be helpful to determine why it runs in a given matter.
For instance right now I am monitoring a single table, data_only import that was started with parallel=8 in the command, but the import job is only using a single thread to do the import, as shown by the following hint the insert query /+ PARALLEL("XXXXX",1)+/. If the process would use the maximum 8 threads specified to should run much faster.