On Thu, Feb 1, 2018 at 9:04 AM, Thomas Munro
<thomas.munro@enterprisedb.com> wrote:
> The cause is running out of DSM slots, but not handing that
> case correctly. I think this implies that you're running queries with
> a lot of Gather [Merge] nodes in them? The number of DSM slots is 64 +
> 2 * max_connections, so one workaround is to crank up max_connections,
> and another is just to disable parallelism for that query.
Or alternatively it could be running out of workers due to the
max_parallel_workers, max_worker_processes limits, which on reflection
may be more likely (the other cases I ran into like this ran out of
DSM slots, because they had very high numbers of Gather nodes).
Either way, it's running out of some resource needed for parallel
query and falling back to non-parallel execution, but Bitmap Heap Scan
had failed to anticipate that possibility.
--
Thomas Munro
http://www.enterprisedb.com