Hi Ne,
i don't know the table definition of JEST out of my mind, but as far as i can remember the columns MANDT and OBJNR are part of the primary key (or even the full primary key), right?
> We are wondering if partitioning the table would let oracle process queries in parallel on this table by default?
No. If you are considering partitioning because of performance issues with that single SELECT, then partitioning won't help. I assume that it uses an unique index (with an unique or range scan) with rowid lookup and does not run a full table or index fast full scan.
As far as i understand you correct, the issue is not the performance of that single SELECT, right? It is more likely the amount of time that is spent by the several executions of that one? Does one SELECT return just one row? If yes, then it is likely caused by "SQL*Net message from client" waits which are considered as an idle event from database perspective, but not from application / SQL response time perspective. I have written a blog post about this topic here ([Oracle / SAP] Thinking clearly about performance and why ASH / AWR based analysis may not be the right approach) some time ago. In such cases you need to rewrite the application code to "bulk" collects / fetches.
Regards
Stefan