[C++][Parquet] When fuzzing, treat Table validation error as hard error

[pitrou]

Describe the enhancement requested

Currently, when fuzzing a Parquet file, proper errors are ignored since the file is most of the time simply invalid: it's ok to get an error.

However, if reading a Parquet row group was successful, the Parquet reader should have ensured that the resulting Table is structurally sound: calling Table::Validate should succeed, and if it fails then it should report a bug.

Table::ValidateFull, however, would still be allowed to fail, as for example a Parquet UTF8 column could contain invalid UTF8 bytes, and we don't detect that when decoding.

Component(s)

C++, Parquet, Continuous Integration

[pitrou]

What do you think @adamreeve @wgtmac ?

[adamreeve]

This makes sense to me. If there are errors in the structure of the data that result in invalid Arrow data, then I would expect the Parquet reader to raise those rather than silently return invalid data.

[wgtmac]

Do we really care about the data read by fuzz reader? IIRC, we don't verify data correctness of column stats, page index, etc.

[pitrou]

It depends what you mean with "data correctness". We don't validate the values themselves, but they should probably be structurally sound if reading doesn't emit an error. For example, reading the statistics should not crash or access uninitialized memory (but it may return values that are consistent with the data values).