Jeff Davis <pgsql(at)j-davis(dot)com> writes:
> In REL8_4_STABLE and REL9_0_STABLE:
> => select ntile(3) OVER ( ORDER BY CASE WHEN count(i) = 0 THEN NULL ELSE
> count(i) END asc ) from ( SELECT NULL::integer as i limit 0 ) s ;
> ERROR: cannot extract attribute from empty tuple slot
I believe this is the same case fixed here:
http://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=c1d9579dd
and as noted in that commit message, it didn't appear worth the risk
of fixing it in released branches.
regards, tom lane