[EPIC] Implement StringViewArray and BinaryViewArray

[alamb]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
Recently two new types were added to the Arrow format that make it more suitable for certain types of operations on strings

Specifically when doing filtering / take with string data, creating a new Utf8Array requires copying the strings to a new, packed binary buffer. The "VariableSizeBinaryView" was designed to solve this limitation and recently added to the Arrow spec.

Describe the solution you'd like
I would like to implement StringViewArray and BinaryViewArray following the spec:
The spec: https://arrow.apache.org/docs/format/Columnar.html#variable-size-binary-view-layout
https://github.com/apache/arrow/blob/3fe598ae4dfd7805ab05452dd5ed4b0d6c97d8d5/format/Schema.fbs#L187-L205

Initially, I would suggest we get the basic types in place:

• Add DataType::Utf8View and DataType::BinaryView #5468
• Add StringViewArray implementation and layout and basic construction + tests #5469
• Add BinaryViewArray implementation and layout and basic construction

Then as follow on PRs, add support for key features

• IPC format support for StringViewArray and BinaryViewArray #5506
• Arrow Flight format support for StringViewArray and BinaryViewArray #5507
• cast kernel support for StringViewArray and BinaryViewArray #5508
• Display support for StringViewArray and BinaryViewArray #5509
• filter kernel support for StringViewArray and BinaryViewArray #5510
• take kernel support for StringViewArray and BinaryViewArray #5511
• cast kernel support for StringViewArray and BinaryViewArray <--> DictionaryArray` #5861
• Implement compare_op for GenericBinaryView  #5897
• Implement arrow-row en/decoding for GenericByteView types #5921
• like benchmark for StringView #5936
• Implement sort for String/BinaryViewArray #5963 (review)
• Implement like/ilike etc for StringViewArray #5931
• Implement benchmarks for compare_op for GenericBinaryView #5903
• Add gcgarbage collector support for StringViewArray and BinaryViewArray #5513
• Implement StringViewArray and BinaryViewArray reading/writing in parquet #5530
• Add arrow IPC cross implementation serialization tests
• Potential performance improvements for reading Parquet to StringViewArray/BinaryViewArray #5904
• Consider implementing some sort of deduplicate / intern functionality for StringView #5910
• New null with view types are not supported #5893
• Min/max support for String/BinaryViewArray #6052
• Default block_size for StringViewArray #6094
• Faster min/max for string/binary view arrays #6088
• interleave (used in Sort)

Potential Follow ons / additional optimizations

• Optimize StringView row decoding #5945
• Improve performance of constructing ByteViews for small strings #6034
• Improve arrow-row --> StringView/BinaryView memory usage  #6057
• Improve speed of row converter by skipping utf8 checks #6058
• Optimize like/ilike kernels for StringView #5951

Describe alternatives you've considered
I think a good plan would be to dust off the prototype on #4585 from @tustvold (linked from #4253).

Initially, the idea would be to dust off the PR and split it into a few smaller PRs with tests and docs.

Additional context
Polars implemented it recently in rust so that can serve as a motivation
Blog Post https://pola.rs/posts/polars-string-type/
https://twitter.com/RitchieVink/status/1749466861069115790

Facebook/Velox's take: https://engineering.fb.com/2024/02/20/developer-tools/velox-apache-arrow-15-composable-data-management/

Related PRs:
pola-rs/polars#13748
pola-rs/polars#13839
pola-rs/polars#13489

[alamb]

@tustvold pointed out the previous PR he made was #4585

We can probably dust that off and get it ready to merge as part of this project

[alamb]

@kallisti-dev I believe may do some work on this.

I suggested breaking it down into a sequence of PRs (keeping notes of what is not yet implemented along the way)

Specifically, I suggest the first PR should have:

1. The new DataType
2. The new StringViewArray and impl Array
3. A basic constructor for creating and validating StringViewArray
4. Any feature (e.g. IPC support, parquet support, etc) should return a Arrow::NotYetImplemented error (rather than panic)

That will likely be a sizeable PR on its own.

[alamb]

Post from Velox on iimportance of stringview: https://engineering.fb.com/2024/02/20/developer-tools/velox-apache-arrow-15-composable-data-management/

[alamb]

Moving an update from @sundy-li and @ariesdevil from #4585 (comment) to here for visibility

I believe @ariesdevil is considering working on this relatively shortly

Hi @alamb, I'm willing to work on this feature after datafuselabs/databend#14662 is finished.

@XiangpengHao, who will be working with us at InfluxData this summer (starting in May) is also interested in this project, so when we get closer to May we'll engage more fully and perhaps we can figure out how to split up some of the work.

[ariesdevil]

Moving an update from @sundy-li and @ariesdevil from #4585 (comment) to here for visibility↳

I believe @ariesdevil is considering working on this relatively shortly↳

Hi @alamb, I'm willing to work on this feature after datafuselabs/databend#14662 is finished.↳

@XiangpengHao, who will be working with us at InfluxData this summer (starting in May) is also interested in this project, so when we get closer to May we'll engage more fully and perhaps we can figure out how to split up some of the work.

Do we have a group similar to Discord or Slack?

[alamb]

Do we have a group similar to Discord or Slack?

@ariesdevil There is both discord and slack -- links are here https://github.com/apache/arrow-rs?tab=readme-ov-file#arrow-rust-community

The discord server doesn't require an invite and seems to be a bit more active recently

[alamb]

@ariesdevil says they have time to begin work on this so I will begin filing subtasks

Update: I filed these two tasks to get us started.

• Add DataType::Utf8View and DataType::BinaryView #5468
• Add StringViewArray implementation and layout and basic construction + tests #5469

[alamb]

Update here is that @ariesdevil has a PR #5481 that we plan to merge tomorrow with the initial array implementations and we'll continue iterating from there

Once that is merged, I'll plan to write some more tickets up

[alamb]

I filed a bunch of follow on tickets, in case anyone cares

#5506
#5507
#5508
#5509
#5510
#5511
#5513

[cgbur]

Is there an issue to make sure that parquet support for the new arrow view types are supported. Currently can not use with the parquet writer when they are specified in the schema.

I am actually more familiar with Arrow than I am Parquet so excuse the question: is there an official Parquet spec or implementation plan for the view types?

[ariesdevil]

I'm working on read/write parquet for view types.

[alamb]

Update here: thanks to @ariesdevil and @XiangpengHao and @RinChanNOWWW we have pretty good basic support for StringView in arrow-rs -- we have basic construction, cast and soon comparison functionality complete. Also, we can now read directly from parquet into StringView arrays #5530

We have also begun the work to integrate this into DataFusion, which is tracked in apache/datafusion#10918

[alamb]

Update here is that most of the basic StringView work for basic scanning / filtering is done. There will likely be an large tail of places to implement special StringView support as follw on.

Over the next week or two I plan to file a new ticket for the remaining known work and close this ticket down

[alamb]

I think we are close to finishing enough of this ticket to claim initial support is done -- I expect we can claim initial support is complete in the 52.2.0 release #5998, due to be released in a few weeks time. Once that is done, I'll open a epic to track remaining / additional work

[alamb]

Given we have now released all the basic support in arrow 52.0.0 am going to claim we are done with the initial implementation and close this ticket 🎉

Huge kudos to everyone who helped including @RinChanNOWWW @ariesdevil @tustvold @XiangpengHao and @a10y (sorry if I forgot anyone)

I am collecting additional potential work items in #6163