Hi,
trying to reproduce a performance problem I just found:
=# CREATE TABLE twocol(col01 int, col02 int);
=# SELECT DISTINCT col01, col02, col01 FROM twocol ;
ERROR: XX000: ORDER/GROUP BY expression not found in targetlist
LOCATION: get_sortgroupref_tle, tlist.c:341
which appears to be a 9.6 regression, presumable fallout from the path
restructuring.
Greetings,
Andres Freund