On Tue, Apr 5, 2022 at 12:42 PM Imseih (AWS), Sami <sims...@amazon.com> wrote: > > Why isn't the obvious thing to do here to provide a way to associate > > workers > > with their leaders in shared memory, but to use the existing progress > > fields > > to report progress? Then, when querying progress, the leader and workers > > progress fields can be combined to show the overall progress? > > The original intent was this, however the workers > can exit before the command completes and the > worker progress data will be lost. > This is why the shared memory was introduced. > This allows the worker progress to persist for the duration > of the command.
At the beginning of a parallel operation, we allocate a chunk of dynamic shared memory which persists even after some or all workers have exited. It's only torn down at the end of the parallel operation. That seems like the appropriate place to be storing any kind of data that needs to be propagated between parallel workers. The current patch uses the main shared memory segment, which seems unacceptable to me. -- Robert Haas EDB: http://www.enterprisedb.com
