Re: BUG #14973: hung queries

Hi Thomas,

I'm glad to help. Thanks for the advice!

By the way, there was a mistake in my bug report - wait_event actually
was BgWorkerShutdown.

Dmitry Shalashov, relap.io & surfingbird.ru

2017-12-18 22:55 GMT+03:00 Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>:

> On Tue, Dec 19, 2017 at 6:38 AM, Thomas Munro
> <thomas(dot)munro(at)enterprisedb(dot)com> wrote:
> > On Fri, Dec 15, 2017 at 1:31 AM, <skaurus(at)gmail(dot)com> wrote:
> >> pg_stat_activity says that they all have wait_event_type = IPC,
> wait_event =
> >> BtreePage, state = active
> >
> > https://www.postgresql.org/message-id/E1ePESn-0005PV-S9%
> 40gemulon.postgresql.org
> >
> > The problem is in Parallel Index Scan for btree. The fix will be in
> > 10.2. One workaround in the meantime would be to disable parallelism
> > for that query (SET max_parallel_workers_per_gather = 0).
>
> On second thoughts, a more targeted workaround to avoid just these
> buggy parallel index scans without disabling parallelism in general
> might be:
>
> SET min_parallel_index_scan_size = '5TB';
>
> (Assuming you don't have any indexes that large.)
>
> --
> Thomas Munro
> http://www.enterprisedb.com
>