On Wed, Apr 6, 2022 at 5:22 PM Imseih (AWS), Sami <sims...@amazon.com> wrote: > > 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. > > Correct, DSM does track shared data. However only participating > processes in the parallel vacuum can attach and lookup this data. > > The purpose of the main shared memory is to allow a process that > Is querying the progress views to retrieve the information.
Sure, but I think that you should likely be doing what Andres recommended before: # 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? That is, I am imagining that you would want to use DSM to propagate data from workers back to the leader and then have the leader report the data using the existing progress-reporting facilities. Now, if we really need a whole row from each worker that doesn't work, but why do we need that? -- Robert Haas EDB: http://www.enterprisedb.com