HDF file compression not working

[WuraolaOyewusi]

xref #28890 (review)

While updating the performance comparison part of the IO docs it was found that compressed size values for .hdf file formats were the same as uncompressed .hdf file formats.

    24009288 Oct 10 06:43 test_fixed.hdf
    24009288 Oct 10 06:43 test_fixed_compress.hdf
    24458940 Oct 10 06:44 test_table.hdf
    24458940 Oct 10 06:44 test_table_compress.hdf

This seems to be caused by the next lines saving the same files:

df.to_hdf('test.hdf', 'test', mode='w')
df.to_hdf('test.hdf', 'test', mode='w', complib='blosc')

We need to see why the complib parameter is being ignored, and fix it so the hdf5 file is saved compressed when used.

CC @datapythonista

[kylekeppler]

Correct URL is https://github.com/pandas-dev/pandas/pull/28890/files

[yp1996]

Hi @WuraolaOyewusi are currently working on this issue? If not, do you mind if I give it a shot?

[WuraolaOyewusi]

@yp1996 . Please go ahead.

[joybh98]

@yp1996 ,are you still working on this? If not I'll like to work on it!

[MarcoGorelli]

@joybhallaa we haven't heard from them in over 2 weeks, so if this is something you'd like to work on I think you're OK to go ahead - please comment 'take' so the issue will be assigned to you

[joybh98]

take

[MarcoGorelli]

Sure - you can see #29404 for a starting point if you like

[joybh98]

@MarcoGorelli , sure will do!

[joybh98]

Hey all,
So I was going through the tests in test_store.py
and the tests have lines

assert node.filters.complevel == 0
assert node.filters.complib is None

These tests are checking for conditions and returning true or false, but not changing the values for these 2 parameters.
Can I use pytest to set values in case of any errors, and use it to set a "default" value, or should I do it in pytables.py.

I may be wrong about some things, as I am still fairly new to pytest.
Open to any suggestions.