jinxing64 opened a new pull request #1351: [CALCITE-3226] Expand view should 
keep the alias expanded view 
URL: https://github.com/apache/calcite/pull/1351
 
 
   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"),
                     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));
       }
     }
   ```

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