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

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

Environment info:
psql --version
psql (PostgreSQL) 13.2 (Ubuntu 13.2-1.pgdg20.04+1)

psql -c 'select version();'
PostgreSQL 13.2 (Ubuntu 13.2-1.pgdg20.04+1) on x86_64-pc-linux-gnu, compiled
by gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0, 64-bit

uname -a
Linux hostname 5.4.0-65-generic #73-Ubuntu SMP Mon Jan 18 17:25:17 UTC 2021
x86_64 x86_64 x86_64 GNU/Linux

pg_ctlcluster 13 main status
pg_ctl: server is running (PID: 595329)
/usr/lib/postgresql/13/bin/postgres "-D" "/var/lib/postgresql/13/main" "-c"
"config_file=/etc/postgresql/13/main/postgresql.conf"


How to reproduce:

createdb test
wget https://www.coreit.cz/download/test.sql.gz
zcat test-plain.sql.gz | psql test
vacuumdb -z test
psql test -X -v VERBOSITY=verbose -c '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;'

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.