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https://issues.apache.org/jira/browse/CALCITE-3226?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16909567#comment-16909567
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jin xing commented on CALCITE-3226:
-----------------------------------
Thanks a lot for clarify [~rubenql]
I think [~julianhyde] expects to add a test case where the view of “select *
from t” expands as a Scan, but I tried and turned out that it always expands as
a Project+Scan.
For a common table scan, the alias would have already been correctly set and I
added a test case
testProjectWithAliasFromScan(https://github.com/apache/calcite/pull/1351/files#diff-9f6a8f13d9ad70d7336340bf6b2e7b71R702)
Thanks a lot for review this issue [~julianhyde][~rubenql] and sorry for my
late reply
> RelBuilder doesn't keep the alias when scan from an expanded view
> -----------------------------------------------------------------
>
> Key: CALCITE-3226
> URL: https://issues.apache.org/jira/browse/CALCITE-3226
> Project: Calcite
> Issue Type: Bug
> Components: core
> Reporter: jin xing
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.21.0
>
> Time Spent: 1h 20m
> Remaining Estimate: 0h
>
> 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".
> {code:java}
> @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));
> }
> }
> {code}
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