asddfl created SPARK-60650:
------------------------------

             Summary: pandas-on-Spark named size aggregation is mapped to SQL 
size and fails on an integer column
                 Key: SPARK-60650
                 URL: https://issues.apache.org/jira/browse/SPARK-60650
             Project: Spark
          Issue Type: Bug
          Components: Pandas API on Spark, PySpark
    Affects Versions: 4.2.0
         Environment: Platform: Ubuntu 24.04 Linux-6.17.0-29-generic x86_64
Python: 3.11.17
pyspark 4.2.0
findspark 2.0.1
pandas 3.0.6
numpy 2.4.6
            Reporter: asddfl


When using the pandas API on Spark (pyspark.pandas), the named aggregation 
agg(c1=('c0', 'size')) fails for an integer column. Pandas returns the group 
size, but pandas-on-Spark generates a SQL size(c0) expression. Spark SQL 
interprets size as the array/map length function and rejects the INT input.

The example uses a single row and an explicitly int32 column. ANSI mode is 
disabled.

{code:python}
import pandas as pd
from pyspark.sql import SparkSession
import pyspark.pandas as ps

t0 = pd.DataFrame({'c0': [1]}, dtype='int32')

print("Pandas:", flush=True)
result = t0.groupby('c0', as_index=False).agg(c1=('c0', 'size'))
print(result, flush=True)

spark = (
    SparkSession.builder
    .master("local[2]")
    .config("spark.sql.ansi.enabled", "false")
    .config("spark.sql.shuffle.partitions", "2")
    .getOrCreate()
)

t0 = ps.DataFrame({'c0': [1]}, dtype='int32')

print("PySpark Pandas:", flush=True)
result = t0.groupby('c0', as_index=False).agg(c1=('c0', 'size'))
print(result, flush=True)

spark.stop()
{code}

{code:bash}
Pandas:
   c0  c1
0   1   1
PySpark Pandas:
Traceback (most recent call last):
  File "/test.py", line 24, in <module>
    result = t0.groupby('c0', as_index=False).agg(c1=('c0', 'size'))
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File 
"/opt/conda/envs/lib/python3.11/site-packages/pyspark/pandas/groupby.py", line 
314, in aggregate
    GroupBy._spark_groupby(self._psdf, func_or_funcs, self._groupkeys)
  File 
"/opt/conda/envs/lib/python3.11/site-packages/pyspark/pandas/groupby.py", line 
406, in _spark_groupby
    sdf = sdf.groupby(*groupkey_names).agg(*reordered)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/conda/envs/lib/python3.11/site-packages/pyspark/sql/group.py", 
line 188, in agg
    jdf = self._jgd.agg(exprs[0]._jc, _to_seq(self.session._sc, [c._jc for c in 
exprs[1:]]))
          
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/conda/envs/lib/python3.11/site-packages/py4j/java_gateway.py", 
line 1362, in __call__
    return_value = get_return_value(
                   ^^^^^^^^^^^^^^^^^
  File 
"/opt/conda/envs/lib/python3.11/site-packages/pyspark/errors/exceptions/captured.py",
 line 257, in deco
    raise converted from None
pyspark.errors.exceptions.captured.AnalysisException: 
[DATATYPE_MISMATCH.UNEXPECTED_INPUT_TYPE] Cannot resolve "size(c0)" due to data 
type mismatch: The first parameter requires the ("ARRAY" or "MAP") type, 
however "c0" has the type "INT". SQLSTATE: 42K09; line 1 pos 0;
'Aggregate [__index_level_0__#3], [__index_level_0__#3, size(c0#1, true) AS 
(c0, size)#4]
+- Project [c0#1 AS __index_level_0__#3, c0#1]
   +- Project [__index_level_0__#0L, c0#1, monotonically_increasing_id() AS 
__natural_order__#2L]
      +- LocalRelation [__index_level_0__#0L, c0#1]
{code}

*Expected behavior*

GroupBy size should count rows in each group. For c0 = 1, the result should 
contain one row with c0 = 1 and c1 = 1, matching Pandas.

*Actual behavior*

The pandas-on-Spark aggregation raises AnalysisException with condition 
DATATYPE_MISMATCH.UNEXPECTED_INPUT_TYPE and SQLSTATE 42K09. The message states 
that size(c0) requires an ARRAY or MAP, but c0 has type INT. The captured 
logical plan contains size(c0, true), rather than a row-count aggregation.




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