BUG: Merge on Ray Engine does not produce the column "_merge" when indicator is True

[castelojb]

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Reproducible Example

i get a KeyError for _merge from the following code


import os
os.environ["MODIN_ENGINE"] = "ray"

import modin.pandas as pd


data1 = {
    'id': [1, 2, 3, 4, 5],
    'name': ['Ana', 'Bruno', 'Carlos', 'Daniela', 'Eduardo'],
    'age': [23, 35, 45, 22, 39]
}

df1 = pd.DataFrame(data1)

data2 = {
    'id': [3, 4, 5, 6, 7],
    'name': ['Carlos', 'Daniela', 'Eduardo', 'Fernanda', 'Gustavo'],
    'age': [5000, 6000, 7000, 8000, 9000]
}

df2 = pd.DataFrame(data2)

df_merged = df1.merge(df2, on=['id', 'name'], how='left', indicator=True)

# key error
df_merged[df_merged['_merge'] == 'both']

Issue Description

The issue is that Modin's merge operation does not support the indicator=True option, which is available in Pandas. This option typically creates an additional column, _merge, indicating the source of each row after the merge (i.e., whether the row came from the left DataFrame, the right DataFrame, or both).

Expected Behavior

When performing a merge with indicator=True, Modin should add a column _merge that shows whether a row is from the left DataFrame (left_only), the right DataFrame (right_only), or from both (both).

Error Logs

2024-09-05 16:44:04,679	INFO worker.py:1783 -- Started a local Ray instance.
Traceback (most recent call last):
  File "C:\Users\Pichau\WorkSpaceIdeos\partech\aux.py", line 27, in <module>
    df_merged[df_merged['_merge'] == 'both']
  File "C:\Users\Pichau\miniconda3\envs\partech_gloe_update\lib\site-packages\modin\logging\logger_decorator.py", line 144, in run_and_log
    return obj(*args, **kwargs)
  File "C:\Users\Pichau\miniconda3\envs\partech_gloe_update\lib\site-packages\modin\pandas\base.py", line 3948, in __getitem__
    return self._getitem(key)
  File "C:\Users\Pichau\miniconda3\envs\partech_gloe_update\lib\site-packages\modin\logging\logger_decorator.py", line 144, in run_and_log
    return obj(*args, **kwargs)
  File "C:\Users\Pichau\miniconda3\envs\partech_gloe_update\lib\site-packages\modin\pandas\dataframe.py", line 3247, in _getitem
    return self._getitem_column(key)
  File "C:\Users\Pichau\miniconda3\envs\partech_gloe_update\lib\site-packages\modin\logging\logger_decorator.py", line 144, in run_and_log
    return obj(*args, **kwargs)
  File "C:\Users\Pichau\miniconda3\envs\partech_gloe_update\lib\site-packages\modin\pandas\dataframe.py", line 2581, in _getitem_column
    raise KeyError("{}".format(key))
KeyError: '_merge'

Installed Versions

INSTALLED VERSIONS

commit : c8bbca8
python : 3.10.14.final.0
python-bits : 64
OS : Windows
OS-release : 10
Version : 10.0.22621
machine : AMD64
processor : AMD64 Family 23 Model 113 Stepping 0, AuthenticAMD
byteorder : little
LC_ALL : None
LANG : None
LOCALE : pt_BR.cp1252

Modin dependencies

modin : 0.31.0
ray : 2.35.0
dask : 2023.3.2
distributed : 2023.3.2.1

pandas dependencies

pandas : 2.2.0
numpy : 1.24.3
pytz : 2024.1
dateutil : 2.8.2
setuptools : 69.5.1
pip : 24.0
Cython : None
pytest : None
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : 4.9.2
html5lib : None
pymysql : None
psycopg2 : 2.9.6
jinja2 : 3.1.4
IPython : 8.27.0
pandas_datareader : None
adbc-driver-postgresql: None
adbc-driver-sqlite : None
bs4 : 4.12.3
bottleneck : None
dataframe-api-compat : None
fastparquet : 2024.2.0
fsspec : 2024.3.1
gcsfs : None
matplotlib : 3.9.2
numba : 0.57.0
numexpr : None
odfpy : None
openpyxl : 3.1.2
pandas_gbq : None
pyarrow : 17.0.0
pyreadstat : None
python-calamine : None
pyxlsb : None
s3fs : None
scipy : None
sqlalchemy : 2.0.34
tables : None
tabulate : 0.9.0
xarray : 2024.7.0
xlrd : None
zstandard : None
tzdata : 2024.1
qtpy : None
pyqt5 : None
None