Sort Ordering for NULLs in DuckDB vs Postgres

[onderkalaci]

Hi,

Is the following an oversight or the expected behavior for DuckDB?

The docs suggests that the sort ordering is identical to Postgres: ... This is identical to the default sort order of PostgreSQL....

However, it seems like there is a difference between DuckDB and PostgreSQL for DESC ordering with NULL values.

• From Postgres Docs: NULLS FIRST is the default for DESC order, and NULLS LAST otherwise.
• From DuckDB docs: default is NULLS LAST

And, this is in action where the outputs are different for Postgres and Duckdb:

Postgres:

CREATE TABLE orderby_test (a int);
INSERT INTO orderby_test VALUES (1), (NULL);
SELECT * FROM orderby_test ORDER BY a DESC;
 a 
---
  
 1
(2 rows)

Duckdb:

D CREATE TABLE orderby_test (a int);
D INSERT INTO orderby_test VALUES (1), (NULL);
D SELECT * FROM orderby_test ORDER BY a DESC;
┌───────┐
│   a   │
│ int32 │
├───────┤
│     1 │
│       │
└───────┘
D 

[Tishj]

SET default_null_order='postgres'

[onderkalaci]

Nice, thanks for the tip!