[CALCITE-3226] RelBuilder doesn't keep the alias when scan from an expanded view

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.21.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Jin Xing
• Reporter: Jin Xing
• Created: 02/Aug/19 06:36
• Updated: 10/Sep/19 21:36
• Resolved: 08/Aug/19 07:00

Description

In current implementation of RelBuilder::scan (https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/tools/RelBuilder.java#L1048), the alias can be derived and recorded into Frame only when the RelNode is a TableScan (https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/tools/RelBuilder.java#L2754).
But when RelBuilder::scan from an expanded view, the node is not a TableScan and the alias is not kept.  Below test failed - we cannot reference a field by alias "MYVIEW".

  @Test public void testExpandViewShouldKeepAlias() throws SQLException {
    try (Connection connection = DriverManager.getConnection("jdbc:calcite:")) {
      final Frameworks.ConfigBuilder configBuilder =
          expandingConfig(connection);
      final RelOptTable.ViewExpander viewExpander =
          (RelOptTable.ViewExpander) Frameworks.getPlanner(configBuilder.build());
      final RelFactories.TableScanFactory tableScanFactory =
          RelFactories.expandingScanFactory(viewExpander,
              RelFactories.DEFAULT_TABLE_SCAN_FACTORY);
      configBuilder.context(Contexts.of(tableScanFactory));
      final RelBuilder builder = RelBuilder.create(configBuilder.build());
      RelNode node =
          builder.scan("MYVIEW")
              .project(
                  builder.field(1, "MYVIEW", "EMPNO"),           // Exception thrown from here.
                  builder.field(1, "MYVIEW", "ENAME"))
              .build();
      String expected =
          "LogicalProject(EMPNO=[$0], ENAME=[$1])\n"
              + "  LogicalFilter(condition=[=(1, 1)])\n"
                  + "    LogicalTableScan(table=[[scott, EMP]])\n";
      assertThat(node, hasTree(expected));
    }
  }

Issue Links

• links to: GitHub Pull Request #1351