Issue upserting with parent external id tSalesforceOutputBulkExec

[nidhin_san]

Hello Everyone,

I have a requirement to upsert a list of contacts with an external id (LP_ExternalContactId__c) and also need to relate to the account with another external id (LP_ExternalClientId__c). I am using tSalesforceOutputBulkExec (Bulk API V1) for this as I have to do a retry mechanism on failure. So the first try is in Parallel concurrency mode with a bigger batch size and the retry in serial mode with a smaller batch size. Now that the reject file populated is having the parent external id value as blank. For this reason, my retry job loads all the contacts without the account ids for the ones that are failing where account is not present. It populates the parent external id value in the reject file if I enable Bulk API V2, but I cannot use V2 as it doesn't allow us to select the concurrency mode and batch size. Below are some of the screenshots. Any help would be appreciated.

Its a very common scenario, but I have spend more than a day with it finding the root cause.

Version used