GeezerVison

What I ran: ./build.sh (with Calcite at 4bf922b), then mvn test -Dtest=TopKTests,FloatingPointEqualityTests,NegativeParserTests,ArrayTests,DocumentationTests and pre-commit run on the changed files. pre-commit passes, and so do all the new tests.

bug (high): NegativeParserTests.errorTest fails. The Calcite bump changes what "This is not SQL" reports. It used to be Non-query expression encountered in illegal context; now it is Encountered "not SQL". Was expecting one of: .... I set isDistinctOnAllowed() back to false and the test still failed, so the bump causes it, not DISTINCT ON. It probably affects #6599 too. Please update the test's expected message.

missing (medium): test coverage. I wrote these QA cases as incremental tests (StreamingTestBase). None are in the PR:

The PR's distinctOn tests only run in the non-incremental SqlIoTest, so nothing checks retractions. I suggest adding at least the retraction case to TopKUnusedFieldsIncrementalTests or a StreamingTestBase class:

@Test
public void distinctOnIncremental() {
    var ccs = this.getCCS("""
            CREATE TABLE T(a INT, b INT, c INT);
            CREATE VIEW V AS SELECT DISTINCT ON (a) a, b, c FROM T ORDER BY a, b DESC;""");
    ccs.step("INSERT INTO T VALUES (1, 1, 10), (1, 2, 20), (2, 5, 30);", """
             a | b | c  | weight
            ---------------------
             1 | 2 | 20 | 1
             2 | 5 | 30 | 1""");
    ccs.step("INSERT INTO T VALUES (1, 3, 40);", """
             a | b | c  | weight
            ---------------------
             1 | 2 | 20 | -1
             1 | 3 | 40 | 1""");
    ccs.step("REMOVE FROM T VALUES (1, 3, 40);", """
             a | b | c  | weight
            ---------------------
             1 | 3 | 40 | -1
             1 | 2 | 20 | 1""");
}

Also, this PR still contains the UNNEST commit from #6599, so it should be rebased once #6599 merges.