[AVRO-3570] Logical type with "fixed" type not interoperable

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.11.0
• Component/s: csharp, doc, logical types, rust

Language

C# Rust

• Assignee: Unassigned
• Reporter: Kalle Niemitalo
• Created: 03/Jul/22 15:48
• Updated: 04/Oct/23 08:26

Description

The Avro specification does not include examples on how to apply the "decimal" or "duration" logical type to a "fixed" type. The implementations disagree on what the correct JSON structure is.

The C++, Java, Python, and Ruby libraries expect the properties of the "fixed" type to be in the same JSON object as the properties of the logical type:

{
    "type": "fixed",
    "name": "test.FixedDecimal",
    "size": 8,
    "logicalType": "decimal",
    "precision": 18,
    "scale": 4
}

The C# and Rust libraries instead expect a nested JSON object for the "fixed" type:

{
    "type": {
        "type": "fixed",
        "name": "test.Fixed8",
        "size": 8
    },
    "logicalType": "decimal",
    "precision": 18,
    "scale": 4
}

Schemas using types like this are then not interoperable between languages.

Issue Links

• incorporates: AVRO-3869 Error parsing fixed logical schemas
• is related to: AVRO-3780 [Rust] Bug: decimal logical type usage through Fixed schema
• relates to: AVRO-3477 Add unit tests for logical types with fixed base type