Make table protocol version / table features easily accessible

[MrPowers]

Description

There is a deltalake.table.ProtocolVersion interface here, but I don't fully understand it. I guess this is for changing the protocol versions of a table?

Is there a way to fetch the reader_version & writer_version for a table?

Is there a way to fetch all the table features that are enabled for a table?

[wjones127]

That's the return value of the DeltaTable.protocol() method.

delta-rs/python/deltalake/table.py

Line 413 in 7d2bb27

def protocol(self) -> ProtocolVersions:

For some reason this method isn't documented.

[wjones127]

Oh it's probably just because it doesn't have a docstring. Anyone want to make a PR to add one?

[MrPowers]

@wjones127 - getting this documented would be awesome!

What do you think about another table_features method that returns the table features that are enabled for a table? If the protocol() method returns 3,7, then the user still won't know what table features are enabled.

[wjones127]

What do you think about another table_features method that returns the table features that are enabled for a table? If the protocol() method returns 3,7, then the user still won't know what table features are enabled.

Perhaps this could be another field on ProtocolVersions, since it is part of the versioning info? Something like:

class ProtocolVersions(NamedTuple):
    min_reader_version: int
    min_writer_version: int
    table_features: List[str]

[ion-elgreco]

What do you think about another table_features method that returns the table features that are enabled for a table? If the protocol() method returns 3,7, then the user still won't know what table features are enabled.

Perhaps this could be another field on ProtocolVersions, since it is part of the versioning info? Something like:

class ProtocolVersions(NamedTuple):
    min_reader_version: int
    min_writer_version: int
    table_features: List[str]

Currently we can access them I saw, with dt.metadata().configuration

[Jan-Schweizer]

I'd like to try myself on this issue.
The task is to extend the pub struct Protocol here like so:

pub struct Protocol {
    pub min_reader_version: i32,
    pub min_writer_version: i32,
    pub reader_features: Option<Vec<String>>,
    pub writer_features: Option<Vec<String>>,
}

Also, the DeltaTableState should be extended with reader_features: Option<Vec<String>>, and writer_features: Option<Vec<String>>,.

Is this understanding correct?

Edit: I've seen that this issue will be taken care of with this PR.