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https://issues.apache.org/jira/browse/CALCITE-4729?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17400323#comment-17400323
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duan xiong commented on CALCITE-4729:
-------------------------------------
[~julianhyde] Hi. When I try to resolve this issue. I find some test code
[Unit Test
|https://github.com/apache/calcite/blob/master/core/src/test/java/org/apache/calcite/test/SqlToRelConverterTest.java#L694]
And I noticed the Java doc about the "referencing columns from a sub-query
that has duplicate column names is illegal". So I want to know whether we need
to do this? And In Calcite, I fund represent a column with a unique column
name in scope. So If we decided to change this. I need some advice. Thank you
very much.
Some UT(throw info:Column 'cust_id' is ambiguous)
{code:java}
select * from (select s.\"cust_id\", s.\"cust_id\"\n" + "from
\"foodmart\".\"sales_fact_1997\" as s)
{code}
> Column in CTE should be ambiguous
> ---------------------------------
>
> Key: CALCITE-4729
> URL: https://issues.apache.org/jira/browse/CALCITE-4729
> Project: Calcite
> Issue Type: Bug
> Components: core
> Reporter: Lantao Jin
> Assignee: duan xiong
> Priority: Major
>
> {code}
> create table test (a int);
> with t as
> (
> select * from test t1 join test t2 on t1.a=t2.a
> )
> select t.a from t;
> {code}
> The above query fails with 't.a' is ambiguous in Spark/Presto/Postgres. But
> it succeeds in Calcite. Currently, many and many companies use Calcite as a
> query federation layer upon multiple query engines such as Spark and Presto.
> But this behavior confused users.
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