[AVRO-3780] [Rust] Bug: decimal logical type usage through Fixed schema

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.12.0, 1.11.2
• Component/s: rust
• Labels: pull-request-available
• External issue URL: https://github.com/apache/avro/pull/2283

Language

Rust

• Assignee: Martin Tzvetanov Grigorov
• Reporter: Fedor Telnov
• Created: 13/Jun/23 14:26
• Updated: 04/Oct/23 08:26
• Resolved: 14/Jun/23 10:18

Description

Currently, fixed type almost could not be used to represent decimal logical type.

What am I trying to do is to parse such a schema:

{
    "type": "record",
    "name": "recordWithDecimal",
    "fields": [
        {
            "name": "decimal",
            "type":   {
                 "type": "fixed",    "name": "nestedFixed",       "size": 8,   "logicalType": "decimal",     "precision": 4
            }
         }
    ],
}

It must be working if we strictly follow the avro specs. It does not work on master - you can see it through the test I supplied in the attached PR.

Interestingly, such a thing works with bytes, so following schema works great:

{
    "type": "record",
    "name": "recordWithDecimal",
    "fields": [
    {
        "name": "decimal",
        "type":
        {   "type": "bytes",   "name": "nestedFixed",      "logicalType": "decimal",     "precision": 4  }
    }
    ],
}

And the only existing workaround is to extract decimal attributes to the field declaration, like so:

{
    "name": "decimal",
    "type":
        {      "type": "fixed",     "name": "nestedFixed"    },
     "size": 8,
     "logicalType": "decimal",
     "precision": 4
}

Such a workaround should not be treated as an acceptable variant as it does not follow avro specification at all(I think, such a syntax is an extension, introduced in the Rust crate - correct me if I'm wrong).
 

I haven't investigated the roots yet, so any thoughts are welcome before I do it myself.

 

Issue Links

• relates to: AVRO-3570 Logical type with "fixed" type not interoperable
• links to: GitHub Pull Request #2283