This is just a short note about one of the potential side-effects of the new Auto Degree Of Parallelism (DOP) feature introduced in 11.2.
If you happen to have Parallel DML enabled in your session along with Auto DOP (and here I refer to the PARALLEL_DEGREE_POLICY = AUTO setting, not LIMITED) then it might take you by surprise that INSERT statements that are neither decorated with a parallel hint nor use any parallel enabled objects can be turned into direct-path inserts.
It looks like Oracle has introduced with the Oracle 18.104.22.168 patch set a new "cost is time" model for the time estimate of the Cost-Based Optimizer (CBO).
In order to understand the implications let me summarize the evolution of the CBO in terms of cost / time estimate so far:
1. Oracle 7 and 8