[GitHub] [arrow-datafusion] waynexia opened a new issue, #6489: Substrait doesn't support alias in projection

["waynexia (via GitHub)" <gi...@apache.org>]

waynexia opened a new issue, #6489:
URL: https://github.com/apache/arrow-datafusion/issues/6489

   ### Describe the bug
   
   SQLs like these will fail:
   ```sql
   SELECT a as alias_a, a FROM data;
   ```
   or
   ```sql
   SELECT a as alias_a FROM data ORDER BY a;
   ```
   
   The error message looks like
   ```
   Error: Plan("Projections require unique expression names but the expression \"data.a\" at position 0 and \"data.a\" at position 1 have the same name. Consider aliasing (\"AS\") one of them.")
   ```
   
   ### To Reproduce
   
   Adding case in `datafusion/substrait/tests/roundtrip_logical_plan.rs` like:
   
   ```rust
       #[tokio::test]
       async fn roundtrip_alias_in_projection() -> Result<()> {
           roundtrip("SELECT a as alias_a, a FROM data").await
       }
   ```
   
   ### Expected behavior
   
   It should generate correct LogicalPlan without error
   
   ### Additional context
   
   _No response_


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Re: [I] Substrait doesn't support alias in projection [arrow-datafusion]

["waynexia (via GitHub)" <gi...@apache.org>]

waynexia commented on issue #6489:
URL: https://github.com/apache/arrow-datafusion/issues/6489#issuecomment-1807695779

   https://github.com/apache/arrow-datafusion/pull/5077/files#diff-7bd0ab7829b96498566ab887a4003134c38092e96441b8f5c8ccdb297478884eR384-R386 processes `Expr::Alias` but it isn't supported yet.
   
   ```rust
   #[tokio::test]
   async fn roundtrip_field_alias() -> Result<()> {
       roundtrip("SELECT data.a as b FROM data").await
   }
   ```
   Fails with
   ```
   Projection: data.a AS b
     TableScan: data projection=[a]
   TableScan: data projection=[a]
   thread 'cases::roundtrip_logical_plan::roundtrip_field_alias' panicked at 'assertion failed: `(left == right)`
     left: `"Projection: data.a AS b\n  TableScan: data projection=[a]"`,
    right: `"TableScan: data projection=[a]"`
   ```


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