[GitHub] [arrow-datafusion] alamb commented on pull request #3882: simplify unqualified col name aliases

[GitBox <gi...@apache.org>]

alamb commented on PR #3882:
URL: https://github.com/apache/arrow-datafusion/pull/3882#issuecomment-1284561242

   Here is what postgres does:
   
   ```
   postgres=# select * from foo;
    val | time 
   -----+------
    A   |  1.0
    B   |  2.0
    C   |  3.0
   (3 rows)
   
   postgres=# select trim(val), trim(val) from foo;
    btrim | btrim 
   -------+-------
    A     | A
    B     | B
    C     | C
   (3 rows)
   
   postgres=# 
   ```
   
   Here is what datafusion-cli does from master:
   
   ```
   DataFusion CLI v13.0.0
   ❯ create table foo as select column1 as val, column2 as time from (values ('A', 1.0), ('B', 2.0), ('C', 3.0)) as sq;
   
   0 rows in set. Query took 0.023 seconds.
   ❯ select trim(val), trim(val) from foo;
   Plan("Projections require unique expression names but the expression \"trim(foo.val)\" at position 0 and \"trim(foo.val)\" at position 1 have the same name. Consider aliasing (\"AS\") one of them.")
   ```


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