Re: BUG #16965: Select query fails with ERROR: XX000: could not find pathkey item to sort

On Thu, Apr 15, 2021 at 04:05:03PM +0000, PG Bug reporting form wrote:
> The following bug has been logged on the website:
> 
> Bug reference:      16965
> Logged by:          Jakub Zemanek
> Email address:      jakub.zemanek@gmail.com
> PostgreSQL version: 13.2
> Operating system:   Ubuntu 20.04
> Description:        
> 
> Hi,
> after upgrade of our zabbix database from v 12 to v 13, we have encountered
> error in select queries. When we SET max_parallel_workers_per_gather=0; then
> the query finishes without error. The query looks like this:
> SELECT DISTINCT COUNT(DISTINCT t.triggerid) AS rowscount,i.hostid FROM
> triggers t,functions f,items i WHERE i.hostid=10406 AND
> f.triggerid=t.triggerid AND f.itemid=i.itemid AND t.flags IN (0,4) GROUP BY
> i.hostid;'
> ERROR:  XX000: could not find pathkey item to sort
> LOCATION:  prepare_sort_from_pathkeys, createplan.c:6013

This issue was reported on April 12 by someone else:

    https://www.postgresql.org/message-id/flat/91f3ec99-85a4-fa55-ea74-33f85a5c651f%40swarm64.com

A patch to fix it is being considered.  You might want to watch that
thread to test or apply the patch, or wait for a fix in the next minor
release.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  If only the physical world exists, free will is an illusion.