[Bug]: Upgrading to python v1.2.0 spams my console with warnings I don't understand

[vancromy]

What happened?

Something was changed in the logging behaviour between 1.1.4 and 1.2.0 that is causing a lot of warnings to come from delta_kernel which to me as a user make no sense. Here is an example of this:

2025-10-21T11:10:52Z WARN delta_kernel::listed_log_files] Found file 00000000000000000003.parquet with unknown file type Unknown at version 3

Downgrading back to 1.1.4 makes these disappear. What action should I as a user take based on this warning message?

Expected behavior

No warning level output if not necessary or a more useful warning message if it is actually a warning.

Operating System

Linux

Binding

Python

Bindings Version

1.2.0

Steps to reproduce

Not too sure how I can provide an MRE because access to our deltatables is not allowed.

Relevant logs

[2025-10-21T11:10:52Z WARN delta_kernel::listed_log_files] Found file 00000000000000000003.parquet with unknown file type Unknown at version 3

[ion-elgreco]

cc @roeap @zachschuermann

[rtyler]

What this looks like to me is that there are files in the _delta_log/ directory that are not supposed to be there. Can you share the full prefix/path from the root of the object store for that file?

[roeap]

^^ what @rtyler said ...

[vancromy]

Sure! Thanks for the quick support btw.

I'm not too sure what it is you are after but hopefully this helps.

I'm using delta-rs to connect to an Azure Fabric deltalake table using the abfss protocol. The table has a path like so:
abfss://<fabric-workspace-name>@onelake.dfs.fabric.microsoft.com/<Lakehouse-Name>/Tables/<schema>/<table-name>

Here's what the contents of the folder for that table contains:

There are a few more jsons and parquet files that are not in the screenshot. But nothing of note.

Each one of those files has the following abfss uri:
abfss://<fabric-workspace-name>@onelake.dfs.fabric.microsoft.com/<Lakehouse-Name>/Tables/<schema>/<table-name>/_delta_log/00000000000000000015.json

*** EDIT ***

It seems the files the warnings are referring to are deep in the _delta_log/stats/latest_v1 folder.

[vancromy]

And the stack trace when connecting to that table with the DeltaTable class:

[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000000.parquet with unknown file type Unknown at version 0
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000001.parquet with unknown file type Unknown at version 1
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000002.parquet with unknown file type Unknown at version 2
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000003.parquet with unknown file type Unknown at version 3
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000004.parquet with unknown file type Unknown at version 4
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000005.parquet with unknown file type Unknown at version 5
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000006.parquet with unknown file type Unknown at version 6
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000007.parquet with unknown file type Unknown at version 7
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000008.parquet with unknown file type Unknown at version 8
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000009.parquet with unknown file type Unknown at version 9
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000010.parquet with unknown file type Unknown at version 10
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000011.parquet with unknown file type Unknown at version 11
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000012.parquet with unknown file type Unknown at version 12
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000013.parquet with unknown file type Unknown at version 13
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000014.parquet with unknown file type Unknown at version 14
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000015.parquet with unknown file type Unknown at version 15
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000016.parquet with unknown file type Unknown at version 16
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000017.parquet with unknown file type Unknown at version 17
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000018.parquet with unknown file type Unknown at version 18
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000019.parquet with unknown file type Unknown at version 19
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000020.parquet with unknown file type Unknown at version 20
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000021.parquet with unknown file type Unknown at version 21
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000022.parquet with unknown file type Unknown at version 22
[2025-10-21T14:49:45Z WARN  delta_kernel::listed_log_files] Found file 00000000000000000023.parquet with unknown file type Unknown at version 23

[ion-elgreco]

@vancromy what files are under _commits and _stats?

[vancromy]

@ion-elgreco _commits is empty and _stats contains two subfolders:

1. _latest_v1 - > contains all the parquet files mentioned in the above warnings and a _last_stats folder
2. _raw_v1 - > contains a bunch of parquet files on form part-<alphanumerics>.snappy.parquet

[ion-elgreco]

@rtyler can you transfer the issue to kernel-rs? I think kernel shouldn't throw warnings on files that are in a subdirectory

[vancromy]

For completeness, here is a ls of the dir:

[rtyler]

Thanks for the details @vancromy , this is a great example of fun and esoteric differences in the wild with real Delta tables 😄 This looks like Fabric is adding some additional nonstandard metadata in _delta_log/ that the kernel implementation is not expecting.

This should be a fairly simple fix however