GROUPING SETS and SQL standard

Hi,

We are still on the process to migrate our applications from proprietary RDBMS to PostgreSQL.

Here is a simple query executed on various systems (real query is different but this one does not need any data) :

Connected to:

Oracle Database 19c Standard Edition 2 Release 19.0.0.0.0 - Production

Version 19.3.0.0.0

SQL> select count(*) from (select 1 from dual where 0=1 group by grouping sets(())) tmp;

COUNT(*)

----------

0

select @@version;

GO

--------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------- ------------------------------------------------------

Microsoft SQL Server 2017 (RTM-CU16) (KB4508218) - 14.0.3223.3 (X64)

Jul 12 2019 17:43:08

Copyright (C) 2017 Microsoft Corporation

Developer Edition (64-bit) on Linux (Ubuntu 16.04.6 LTS)

select count(*) from (select 1 as c1 where 0=1 group by grouping sets(())) tmp;

GO

-----------

0

(1 rows affected)

select version();

version

----------------------------------------------------------------------------------------------------------------

PostgreSQL 11.5 (Debian 11.5-1+deb10u1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 8.3.0-6) 8.3.0, 64-bit

select count(*) from (select 1 from dual where 0=1 group by grouping sets(())) tmp;

count

-------

1

(1 ligne)

0 or 1, which behaviour conforms to the SQL standard ? We have a workaround and it's just informational.

Regards,

Phil