dongjoon-hyun edited a comment on issue #27233: [SPARK-29701][SQL] Correct behaviours of group analytical queries when empty input given URL: https://github.com/apache/spark/pull/27233#issuecomment-577487224 @tgravescs . Yes, it does. However, this is correctly a **SQL correctness** issue. Technically, among them, `PostgreSQL` is the only one implementing it according to the SQL standard. `SQL:1999` defines `()` as the `grand total` and the query is translated into the following roughly. ```sql ... (other clause) UNION ALL SELECT CAST(NULL AS DTPC1) AS CNPC1, CAST(NULL AS DTPC2) AS CNPC2, ... # `grand total` FROM ... ``` The test case in this PR description has been used in PostgreSQL community from the beginning of its `Support GROUPING SETS, CUBE and ROLLUP` commit (May 15, 2015) - https://github.com/postgres/postgres/commit/f3d3118532175541a9a96ed78881a3b04a057128#diff-3472ecc50256022c66e79b1aad4075d2R78 As another DBMS, `Presto` supports this like `PostgreSQL`. ``` presto:default> create table gstest_empty (a integer, b integer, v integer); CREATE TABLE presto:default> select a, b, sum(v), count(*) from gstest_empty group by grouping sets ((a,b),()); a | b | _col2 | _col3 ------+------+-------+------- NULL | NULL | NULL | 0 (1 row) ```
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