[ARROW-9275] [Rust] – Async Sans IO: R/W into/to Arrow Arrays

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Invalid
• Component/s: Rust
• External issue URL: https://github.com/apache/arrow/issues/25369
• Assignee: Mahmut Bulut
• Reporter: Mahmut Bulut
• Created: 30/Jun/20 10:28
• Updated: 11/Jan/23 08:05
• Resolved: 26/Apr/21 12:31

Description

This issue can be considered an epic level that spans across other arrow projects.

Drill down

Currently, traits like `ParquetReader` only allow synchronous interface which uses BufReader having 8KB constant buffer. Over the network, this becomes a problem. This can be easily solvable with differential buffers. In addition to this shortage, there is a problem of executor engine is needed to schedule from async trait methods to sync trait methods which should sit somewhere in between to make requests asynchronous to external IO. On-disk IO is acceptable with the approach we currently have since no reliable evented IO exists for on-disk IO on major platforms.

All these considered abstractions that will expose asynchronous IO without any side from executors, needs to be exposed.

 

Design Suggestions & Considerations

The design should apply and consider:

• Sans IO, (for more information about Sans approach please see https://sans-io.readthedocs.io/ ) 
• Not including any executor specific data, at all.
• Tests should work with any executor with little to no modification.
• Buffers are adjusted accordingly and use differential buffers to optimize network trips.
• Sync IO shouldn't be touched. At all costs. If we try to unify Sync IO traits or we do overlapping implementation, that will make our life harder in the future. Sans IO should be compartmentalized.

 

Notes

If Sans approach is not taken, the project will:

• use an extreme amount of dependencies.
• be not compatible with other Rust code at all.
• break currently working code uses array ingestions.
• integrations tests are going to be harder.
• it will really hard to adapt to completion-based APIs stabilize in the future. (in the user projects)
• this suggestion is not about the flight format or any flight-related information atm. This is purely making on-disk, remote IO (provider backends like AWS etc.) async.

 

Open points

A couple of open points:

• Identifying traits that are going to be asyncized.
• Designing internal routines.
• package name to expose.
• Gather traits into the designated packages in all file formats.