Tim Perkins created AVRO-2258:
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Summary: Resolution Canonical Form
Key: AVRO-2258
URL: https://issues.apache.org/jira/browse/AVRO-2258
Project: Apache Avro
Issue Type: New Feature
Components: spec
Reporter: Tim Perkins
The spec defines the Parsing Canonical Form to identify schemas that are the
same from the perspective of reading data written against the schemas. Schema
Fingerprints can then be computed based on the Parsing Canonical Form.
For our implementation of an Avro schema registry, we found schema fingerprints
based on the Parsing Canonical Form to be insufficient because they exclude
default and alias attributes which affect resolution between different schemas.
For the registry, we wanted new versions to created when defaults or alias are
changed.
We extended to the Parsing Canonical Form to define a Resolution Canonical Form
by modifying the order transformation and adding a transformation on aliases:
* [ORDER] Order the appearance of fields in JSON objects as follows: {{name,
type, fields, symbols, items, values, size, default, aliases}}
* [ALIASES] Aliases for named types and fields are converted to their
fullname, using applicable namespace, and sorted.
We have an implementation for this that we have been using in Ruby:
[https://github.com/salsify/avro-resolution_canonical_form]
I'm opening this issue to gauge if there is interest and support for adding
this to the Avro specification. If there is then I can open a pull request to
modify the spec.
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