timsaucer opened a new issue, #17630:
URL: https://github.com/apache/datafusion/issues/17630

   ### Describe the bug
   
   When creating a lag function we are getting an unwanted projection when used 
with `with_column` on a dataframe. See the minimal reproducible example below.
   
   This appears related to https://github.com/apache/datafusion/pull/12000
   
   ### To Reproduce
   
   ```rust
   use arrow::array::{Int32Array, RecordBatch};
   use arrow::datatypes::{DataType, Field, Schema};
   use datafusion::error::Result as DataFusionResult;
   use datafusion::prelude::SessionContext;
   use datafusion_catalog::MemTable;
   use datafusion_expr::col;
   use datafusion_functions_window::expr_fn::lag;
   use std::sync::Arc;
   
   #[tokio::test]
   async fn with_column_lag() -> DataFusionResult<()> {
       let schema = Schema::new(vec![Field::new("a", DataType::Int32, true)]);
   
       let batch = RecordBatch::try_new(
           Arc::new(schema.clone()),
           vec![Arc::new(Int32Array::from(vec![1, 2, 3, 4, 5]))],
       )?;
   
       let ctx = SessionContext::new();
   
       let provider = MemTable::try_new(Arc::new(schema), vec![vec![batch]])?;
       ctx.register_table("t", Arc::new(provider))?;
   
       let df = ctx.table("t").await?;
   
       let lag_expr = lag(col("a"), Some(1), None);
   
       df.with_column("lag_val", lag_expr)?.show().await?;
   
       Ok(())
   }
   ```
   
   Generates output:
   
   ```
   
+---+---------------------------------------------------------------------------------+---------+
   | a | lag(t.a,Int64(1),NULL) ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED 
FOLLOWING | lag_val |
   
+---+---------------------------------------------------------------------------------+---------+
   | 1 |                                                                        
         |         |
   | 2 | 1                                                                      
         | 1       |
   | 3 | 2                                                                      
         | 2       |
   | 4 | 3                                                                      
         | 3       |
   | 5 | 4                                                                      
         | 4       |
   
+---+---------------------------------------------------------------------------------+---------+
   ```
   
   ### Expected behavior
   
   The output above should only contain two columns, `a` and `lag_val`.
   
   ### Additional context
   
   _No response_


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