[CALCITE-2192] RelBuilder wrongly skips creating an Aggregate that prunes columns, if input is unique

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.16.0
• Component/s: core
• Assignee: Jesús Camacho Rodríguez
• Reporter: Jesús Camacho Rodríguez
• Created: 24/Feb/18 17:49
• Updated: 27/Feb/24 22:24
• Resolved: 25/Feb/18 05:32

Description

Issue can be reproduced with following test:

  @Test public void testAggregate3() {
    final RelBuilder builder = RelBuilder.create(config().build());
    RelNode root =
        builder.scan("EMP")
            .aggregate(
                builder.groupKey(builder.field(1)),
                builder.aggregateCall(SqlStdOperatorTable.COUNT, false, false,
                    null, "C"))
            .aggregate(
                builder.groupKey(builder.field(0)))
            .build();
    assertThat(str(root),
        is(""
            + "LogicalProject(ENAME=[$0])\n"
            + "  LogicalAggregate(group=[{1}], C=[COUNT()])\n"
            + "    LogicalTableScan(table=[[scott, EMP]])\n"));
  }

Without fix, builder will generate following plan, which contains an unnecessary field (in Hive, this results in an assertion error in RelFieldTrimmer):

LogicalAggregate(group=[{1}], C=[COUNT()])
    LogicalTableScan(table=[[scott, EMP]])

Issue Links

• is related to: CALCITE-2946 RelBuilder wrongly skips creation of Aggregate that prunes columns if input produces one row at most