Support casting from UTF8 --> FixedSizeBinary, Binary --> FixedSizedBinary
- Dominant language
- Rust
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Description
**Is your feature request related to a problem or challenge? Please describe what you are trying to do.**
A user reported on discord that they were trying to use DataFusion to query FixedSizeBinary fields stored in parquet?
Message link:
https://discord.com/channels/885562378132000778/885562378132000781/1083347011497119775
There is probably a whole project to fully support FixedSizeBinary fields, but initially at least it would be nice to be able to cast them to types that DataFusion has better support for (like Binary)
**Describe the solution you'd like**
@tustvold filed https://github.com/apache/arrow-rs/issues/3826 to track adding conversion between binary <-> fixed size binary
Once that is available, I expect this to work
```
❯ select arrow_cast('002920a3044b3c9f56e797b8'::bytea, 'FixedSizeBinary(12)');
Error during planning: Cannot automatically convert Binary to FixedSizeBinary(12)
```
Once there is direct support to cast between Utf8 and FixedSizeBinary, I would also expect this to work
```
select arrow_cast('002920a3044b3c9f56e797b8', 'FixedSizeBinary(12)');
Error during planning: Cannot automatically convert Utf8 to FixedSizeBinary(12)
```
**Describe alternatives you've considered**
**Additional context**
Contributor guide
Research direction
Start by reviewing the requested binary-to-fixed-size-binary conversion tracked in apache/arrow-rs#3826, then reproduce the two arrow_cast SQL examples from this issue. Done means DataFusion accepts the requested Binary and Utf8 casts to FixedSizeBinary with the expected size validation.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust, sql
- Domain
- databases
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100