Hello everyone, Consider the following example: ``` -- SQLite version 3.35.5 CREATE TABLE t0 (c0 REAL); INSERT INTO t0(c0) VALUES (1), (NULL), (1); CREATE UNIQUE INDEX idx ON t0(NULL DESC); SELECT * FROM t0 GROUP BY c0; ``` Since the two "1" is equal, the expected output should contain two lines: one is null and the other is 1.0. And yes, the output is exactly what I expect. But when we add a constant to the GROUP BY clause, just like: ``` SELECT * FROM t0 GROUP BY c0, NULL; ``` The "GROUP BY constant" means to group all the candidate records into a group by the constant provided. It's like adding a column to the candidate records, and values this constant. So, there should still be 2 lines. But what we get from the output contains 3 lines. It looks like that SQLite takes the two 1.0 as not equal. If we annotate the CREATE INDEX statement, the output turns to be two lines again. I wonder whether it's a bug. Looking forward to your early reply!