On Mon, Dec 2, 2013 at 1:42 PM, Christophe Taton
<[email protected]> wrote:
> - New extension data type, similar to ProtocolBuffer extensions (incompatible
> change).
Extensions might be implemented as something like:
{"type":"record", "name":"extension", "fields":[
{"name":"fingerprint", "type": {"type":"fixed", "size":16}},
{"name":"payload", "type":"bytes"}
]
}
One could then use this with:
{"type":"record", "name":"Foo", "fields":[
{"name":"bar", "type":"extension"}
]
}
The implementation could then find the schema for the extension at
runtime given its fingerprint. The reader could have a table mapping
fingerprints to schemas.
In particular, the specific compiler, when it sees a schema like:
{"type":"record", "name":"Bar", "isExtension":true, "fields":[
{"name":"x", "type":"long"}
]
}
Might emit code to add entries to the extension mapping table used by
SpecificDatumReader, e.g.:
static {
SpecificData.addExtension(getSchema());
}
Might something like this work?
Doug
