delta-rs can't write to a table if datafusion is not enabled

[zhousun]

I found this when I was trying to use delta-rs to manually write parquet files to delta (so I don't need datafusion).

When creating a table, the minwriter-version will be 2.
So in ProtocolChecker, it will look for 'invariant' in writer_features.

But it is only added when datafusion is enabled:

delta-rs/crates/core/src/operations/transaction/protocol.rs

Line 254 in 2498837

writer_features.insert(WriterFeatures::Invariants);

So effectively, if datafusion is not enabled, delta-rs won't be able to do any write.

[ion-elgreco]

Datafusion is simply a requirement to parse invariants and execute them.

Please look at this comment for what you want: #2204 (comment)