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BUG: ValueError when using hdf select with long select strings #39752

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@skwde

Description

@skwde
  • I have checked that this issue has not already been reported.

  • I have confirmed this bug exists on the latest version of pandas.

  • (optional) I have confirmed this bug exists on the master branch of pandas.


Note: Please read this guide detailing how to provide the necessary information for us to reproduce your bug.

Code Sample, a copy-pastable example

import numpy as np
import pandas as pd

# build dataframe and write to hdf file
t = pd.DataFrame([i for i in range(100)], 
             columns=['A'], 
             index=pd.MultiIndex.from_arrays(
                 [[b for a in range(25) for b in ['a', 'b', 'c', 'd']], 
                  range(100)],
                 names=('la','lb')
             )).sort_index()
hdf_test = pd.HDFStore('test.hdf', mode='a', compression=9)
t.to_hdf(hdf_test, 
         '/test', 
         complevel=9,
        format='table'
        )

# build query strings
query1 = []
query2 = []
for idx in t.index:
    query1.append(
        f"(la == '{idx[0]}' & lb == '{idx[1]}')"
    )
    query2.append(
        f"la == {idx[0]}"
    )
 
query1 = ' | '.join(np.unique(query1))
query2 = ' | '.join(np.unique(query2))

# test queries
hdf_test.select('/test', where="(la == 'a' & lb == '0') | (la == 'a' & lb == '12')") # works
hdf_test.select('/test', where=query2) # works
hdf_test.select('/test', where=query1) # fails with  ValueError: too many inputs

Problem description

The select query fails, I guess the reason is the long query string.

Note, in an earlier pandas version (1.2.1) this triggered a MemoryError instead of the ValueError: too many inputs.

Expected Output

dataframe according to query string. (In above case, the full dataframe t)

Output of pd.show_versions()

INSTALLED VERSIONS

commit : 7d32926
python : 3.9.1.final.0
python-bits : 64
OS : Darwin
OS-release : 19.6.0
Version : Darwin Kernel Version 19.6.0: Thu Oct 29 22:56:45 PDT 2020; root:xnu-6153.141.2.2~1/RELEASE_X86_64
machine : x86_64
processor : i386
byteorder : little
LC_ALL : en_US.UTF-8
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8

pandas : 1.2.2
numpy : 1.20.0
pytz : 2021.1
dateutil : 2.8.1
pip : 21.0.1
setuptools : 49.6.0.post20210108
Cython : None
pytest : None
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 2.11.3
IPython : 7.20.0
pandas_datareader: None
bs4 : None
bottleneck : None
fsspec : None
fastparquet : None
gcsfs : None
matplotlib : 3.3.4
numexpr : 2.7.2
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pyxlsb : None
s3fs : None
scipy : 1.6.0
sqlalchemy : None
tables : 3.6.1
tabulate : None
xarray : None
xlrd : None
xlwt : None
numba : None

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