[CALCITE-3393] RelStructuredTypeFlattener: improve support for functions with struct input

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.22.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Igor Guzenko
• Reporter: Igor Guzenko
• Created: 09/Oct/19 12:22
• Updated: 06/Mar/20 04:35
• Resolved: 22/Oct/19 06:35

Description

1. RelStructuredTypeFlattener doesn't support aggregate functions for struct type column.
Example test case:

  @Test
  public void testAggregateFunctionWithStructInput() {
    final String sql =
        "select count(dn.skill) from sales.dept_nested dn";
    sql(sql).ok();
  }

2. For other functions, except ITEM, flattener uses first nested primitive field from
original struct input. Example test case:

  @Test
  public void testFunctionWithStructInput() {
    final String sql =
        "select json_type(dn.skill) from sales.dept_nested dn";
    sql(sql).ok();
  }

Generated plan:

LogicalProject(EXPR$0=[JSON_TYPE($2.TYPE)])
  LogicalTableScan(table=[[CATALOG, SALES, DEPT_NESTED]])

Issue Links

• blocks: DRILL-7386 Fix count and typeOf functions for struct type
• links to: GitHub Pull Request #1511