[CALCITE-5050] Metadata (RelMdRowCount) should reflect the fact that an Aggregate with no GROUP BY always returns 1 row

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.29.0, 1.30.0
• Fix Version/s: 1.31.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Unassigned
• Reporter: Jing Zhang
• Created: 17/Mar/22 13:42
• Updated: 03/Aug/22 16:21
• Resolved: 25/Mar/22 02:35

Description

Currently, RowCount of aggregate without group keys are unexpected.
The problem could be appear in the following UT:

  @Test void testRowCountAggregateEmptyKey1() {
    fixture()
        .withRelFn(b ->
            b.scan("EMP")
                .aggregate(
                    b.groupKey(),
                    b.count(false, "C"))
                .build())
        .assertThatRowCount(is(1D), is(1D), is(1D));
  }

Now, the above UT would be failed because row count return 1.4D instead of 1D.

Issue Links

• links to: GitHub Pull Request #2746