On Mon, Oct 16, 2023 at 12:31 PM Michael Christofides <mich...@pgmustard.com> wrote: > According to the docs[1]: "In a parallel bitmap heap scan, one process is > chosen as the leader. That process performs a scan of one or more indexes and > builds a bitmap indicating which table blocks need to be visited. These > blocks are then divided among the cooperating processes as in a parallel > sequential scan." > > My understanding is that the "Heap Blocks" statistic is only reporting blocks > for the bitmap (i.e. not the subsequent scan). As such, I think it is correct > that the workers do not report additional exact heap blocks.
I think you're wrong about that. The bitmap index scans are what scan the indexes and build the bitmap. The bitmap heap scan node is what scans the heap i.e. the table, and that is what is divided across the workers. On the patch itself, snapshot_and_stats doesn't strike me as a great name. If we added three more variable-length things would we call the member snapshot_and_stats_and_pink_and_orange_and_blue? Probably better to pick a name that is somehow more generic. -- Robert Haas EDB: http://www.enterprisedb.com
