Hi Hackers, Quoting an excerpt from Chapter 15.2 of postgres' official documentation (versions 12 through latest),
*"Even when a parallel query plan is generated for a particular query, there are several circumstances under which it will be impossible to execute that plan in parallel at execution time."* The documentation goes on to describe cases where the plan cannot be executed in parallel, which includes, *The client sends an Execute message with a non-zero fetch count. See the discussion of the extended query protocol ...* I fail to understand why firing the Execute message with a non-zero fetch count is not being parallelized. Is there a technical limitation here, or is it simply that this is a feature that has not been built yet? I noticed that my query was using the Extended protocol, and suffers from this limitation. As for solutions, I'm aware that using the Simple query protocol gives me the performance I need; but that's not the point of this question. I'd like to fundamentally understand what makes the same parallel-execution behaviour impossible with the Extended query protocol. Thanks, Rohit
