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https://issues.apache.org/jira/browse/AVRO-2918?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17178418#comment-17178418
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Jonathan Rapoport edited comment on AVRO-2918 at 8/16/20, 4:24 AM:
-------------------------------------------------------------------
Sure [~emkornfield]:
Picture this base schema:
{code:json}
{
"type" : "record",
"namespace" : "avro.polymorphism",
"name" : "Person",
"fields" : [
{ "name" : "Name" , "type" : "string" },
{ "name" : "Age" , "type" : "int" }
]
}
{code}
And this inherited schema:
{code:json}
{
"type" : "Person",
"namespace" : "avro.polymorphism",
"name" : "Employee",
"fields" :
[
# already included { "name" : "Name" , "type" : "string" },
# already included { "name" : "Age" , "type" : "int" },
{ "name" : "Position" , "type" : "string" },
{ "name" : "Salary" , "type" : "int" }
]
}
{code}
was (Author: jonirap):
Sure [~emkornfield]:
Picture this base schema:
```json
{
"type" : "record",
"namespace" : "avro.polymorphism",
"name" : "Person",
"fields" : [
{ "name" : "Name" , "type" : "string" }
,
{ "name" : "Age" , "type" : "int" }
]
}
```
And this inherited schema:
```json
{
"type" : "Person",
"namespace" : "avro.polymorphism",
"name" : "Employee",
"fields" : [
\# already included \{ "name" : "Name" , "type" : "string" },
\# already included \{ "name" : "Age" , "type" : "int" },
{ "name" : "Position" , "type" : "string" },
{ "name" : "Salary" , "type" : "int" }
]
}
```
> Schema polymorphism
> -------------------
>
> Key: AVRO-2918
> URL: https://issues.apache.org/jira/browse/AVRO-2918
> Project: Apache Avro
> Issue Type: New Feature
> Components: logical types, misc, spec
> Reporter: Jonathan Rapoport
> Priority: Major
> Labels: features
> Original Estimate: 96h
> Remaining Estimate: 96h
>
> Include the option to use named types as base types for a new schema. Allow
> for MRO generation. Field inheritance.
> The benefits of this approach include:
> * Defining a schema as validation for a certain wire, and so allowing the
> receiver to be certain of the structure of the data (this works today).
> However, defining an extension of this schema, or certain schemas which can
> be normalized to the original schema, but contain additional information,
> will not allow it to be sent over the same wire.
> * Backwards compatibility through inheritance - you never break the old
> schema, thus allowing a long integration period, with no need to recode all
> processes familiar with the schema. The new schema will simply inherit the
> old one, and only add information.
> * Allow for full data control through polymorphism, and the ability to
> replace structures within any supported language.
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