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https://issues.apache.org/jira/browse/AVRO-1347?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14222481#comment-14222481
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Ravi commented on AVRO-1347:
----------------------------
Same here.. If my Writer has upgraded to define aliases and create a Super
Schema (that comprises of the aliases), then my old Readers would cease to work
unless they are changed refer to the new Super Schema. Besides Schema Evolution
mentioned by Igor this would also help different applications with different
upgrade life-cycles to continue to work without getting errored out.
> Improve name and alias matching for named schemas
> -------------------------------------------------
>
> Key: AVRO-1347
> URL: https://issues.apache.org/jira/browse/AVRO-1347
> Project: Avro
> Issue Type: Improvement
> Components: java
> Reporter: Vincenz Priesnitz
> Attachments: AVRO-1347.patch, AVRO-1347.patch
>
>
> When reading an avro file with a named schema, the aliases of the writers
> schema are not taken into account; only the aliases of the readers are
> matched against the writers name. Even if the writers aliases match the
> readers name, the schemas will not be matched.
> For example, the following two enum schemas will not be matched, even though
> they share a common alias.
> {code}
> {
> "type" : "enum",
> "name" : "foo",
> "alias" : "CommonAlias",
> "symbols" : ["LEFT", "RIGHT"]
> }
> {code}
> {code}
> {
> "type" : "enum",
> "name" : "bar",
> "alias" : "CommonAlias",
> "symbols" : ["LEFT", "RIGHT"]
> }
> {code}
> In most cases, the DatumReader resolves records of different names or
> namespaces by matching their fields.
> Unfortunately, there are some cases, where this sort of matching is not
> happening, but just the names are compared:
> * Other named nodes, like enums, fixed or fieldschemas are not matched this
> way.
> * A record inside a union is also only matched by the full name.
> The latter one is especially tricky, since two recordschemas that match
> structurally but differ in name or space, are interexchangable until they are
> put into an union, at which point an exception is thrown.
> I propose that two named schemas are matched, when they share a common name
> or alias.
> I implemented said changes and added a java annotation @AvroAlias(alias,
> space) that allows one to add an alias to a record, enum or field.
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