zhengruifeng opened a new pull request, #45431:
URL: https://github.com/apache/spark/pull/45431
### What changes were proposed in this pull request?
Make `withColumnsRenamed` duplicated column name handling consistent with
`withColumnRenamed`
### Why are the changes needed?
`withColumnsRenamed` checks the column names duplication of output
dataframe, this is not consistent with `withColumnRenamed`:
1, `withColumnRenamed` doesn't do this check, and support output a dataframe
with duplicated column names;
2, when the input dataframe has duplicated column names,
`withColumnsRenamed` always fail, even if the columns with the same name are
not touched at all:
```
In [8]: df1 = spark.createDataFrame([(1, "id2"),], ["id", "value"])
...: df2 = spark.createDataFrame([(1, 'x', 'id1'), ], ["id", 'a',
"value"])
...: join = df2.join(df1, on=['id'], how='left')
...: join
Out[8]: DataFrame[id: bigint, a: string, value: string, value: string]
In [9]: join.withColumnRenamed('id', 'value')
Out[9]: DataFrame[value: bigint, a: string, value: string, value: string]
In [10]: join.withColumnsRenamed({'id' : 'value'})
...
AnalysisException: [COLUMN_ALREADY_EXISTS] The column `value` already
exists. Choose another name or rename the existing column. SQLSTATE: 42711
In [11]: join.withColumnRenamed('a', 'b')
Out[11]: DataFrame[id: bigint, b: string, value: string, value: string]
In [12]: join.withColumnsRenamed({'a' : 'b'})
...
AnalysisException: [COLUMN_ALREADY_EXISTS] The column `value` already
exists. Choose another name or rename the existing column. SQLSTATE: 42711
In [13]: join.withColumnRenamed('x', 'y')
Out[13]: DataFrame[id: bigint, a: string, value: string, value: string]
In [14]: join.withColumnsRenamed({'x' : 'y'})
AnalysisException: [COLUMN_ALREADY_EXISTS] The column `value` already
exists. Choose another name or rename the existing column. SQLSTATE: 42711
In [15]: join.withColumnRenamed('value', 'new_value')
Out[15]: DataFrame[id: bigint, a: string, new_value: string, new_value:
string]
In [16]: join.withColumnsRenamed({'value' : 'new_value'})
AnalysisException: [COLUMN_ALREADY_EXISTS] The column `new_value` already
exists. Choose another name or rename the existing column. SQLSTATE: 42711
```
### Does this PR introduce _any_ user-facing change?
yes
### How was this patch tested?
updated tests
### Was this patch authored or co-authored using generative AI tooling?
no
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