Proposal: `parquet 53.0.0` feature branch

[alamb]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

We are now being careful about breaking changes (see https://github.com/apache/arrow-rs/blob/master/CONTRIBUTING.md#breaking-changes)

This means we can't merger PRs with breaking API changes to main until early August

However there are now three potentially large parquet changes that could conflict with each other and have API changes:

• Add size statistics to ParquetMetaData introduced in PARQUET-2261 arrow-rs#5486 from @etseidl
• Reintroduce: Write Bloom filters between row groups instead of the end  arrow-rs#5933 from @progval
• Add ParquetMetadataWriter allow ad-hoc encoding of ParquetMetadata arrow-rs#6000 from @adriangb

Describe the solution you'd like
Some way to avoid a massive set of merge conflicts when we start merging changes to master for parquet 53

I would also love to be able to review and merge smaller PRs rather than keep several large ones outstanding

Describe alternatives you've considered

I would like to propose we create a feature branch (e.g. parquet-53.0.0) in the arrow-rs repo that we can merge parquet API changes to and develop new features

Once main opens for 53 (in early August) we can merge the branch to main

This approach does require maintenance of the parquet 53 branch and runs the risk of accumulating merge conflicts as it diverges from master. I am willing to help do the proces

Additional context

[adriangb]

If we can't merge breaking changes to main I agree this is the path forward. It's very generous of you to take up that burden.

For what it's worth I don't think apache/arrow-rs#6000 should include breaking changes, if there are any I think they're accidental. I'll double check. I do agree it might cause merge conflicts.

[etseidl]

FWIW I just tried a merge of apache/arrow-rs#5486 and apache/arrow-rs#6000. The only significant conflict was missing (new) arguments for the thrift OffsetIndex and ColumnIndex structs. Shouldn't be hard to integrate those two, but it's probably better for the metadata encoder to merge first (especially since apache/arrow-rs#5486 will now be broken up into smaller chunks). apache/arrow-rs#6045 and apache/arrow-rs#6000 should be easier to reconcile and can probably be merged in any order.

The bloom filter changes seem to be orthogonal to the other two, so I don't anticipate any issues there.

[alamb]

For what it's worth I don't think apache/arrow-rs#6000 should include breaking changes, if there are any I think they're accidental. I'll double check. I do agree it might cause merge conflicts.

Thanks @adriangb -- I agree the first PR won't have API conflicts. However, I expect some iteration on the APIs, so once we have merged / released new API (Stats builder) then any changes we make to the new API will require "breaking changes" so we would have to remember what APIs we have released / haven't released.

Maybe we could put it behind a feature flag or something that made it clear the API would change 🤔

[alamb]

The bloom filter changes seem to be orthogonal to the other two, so I don't anticipate any issues there.

I guess I was imagining the parquet metadata encoder would also potentially have the ability to write bloom filters and thus may be affected by apache/arrow-rs#6000

[alamb]

🤔 maybe I can simply make a 53.0.0-dev branch and we can merge the 53 features there 🤔

[alamb]

The more I think about this the more sense I think it makes to have a 53 feature branch for the next few weeks so we can not build up a massive set of conclits. I plan to create one tomorrow unless there are objections and start merging stuff there to clear the review queue

[etseidl]

The more I think about this the more sense I think it makes to have a 53 feature branch for the next few weeks so we can not build up a massive set of conclits. I plan to create one tomorrow unless there are objections and start merging stuff there to clear the review queue

Sounds good to me. In addition to apache/arrow-rs#6045, I have 3 stacked PRs ready to go, and I also have a plan for integrating with the changes from apache/arrow-rs#6000.

[alamb]

I have created https://github.com/apache/arrow-rs/tree/53.0.0-dev as the branch and will now begin retargeting and merging PRs.

This will likely require me to do some release note finagling but we'll handle that when we get there