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https://issues.apache.org/jira/browse/AVRO-680?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14070470#comment-14070470
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Doug Cutting commented on AVRO-680:
-----------------------------------
The pseudocode pretty much already exists in the Javadoc for
Encoder#writeArrayStart().
http://avro.apache.org/docs/current/api/java/org/apache/avro/io/Encoder.html#writeArrayStart()
Except instead of iterating over a list, it should iterate over a Map and write
each key and value, effectively inlining a call to writeRecord(), as done in
that pseudocode.
We should add a ReflectDatumWriter#writeNonStringMap() method that does this
and is called by ReflectDatumWriter#writeArray() to write non-string maps as
arrays that contain two-element records.
It might also be good to add a test that serializes and deserializes non-string
maps as JSON, using JsonEncoder and JsonDecoder. Checking against a different
encoder/decoder implementation provides greater confidence that the encoder &
decoder interfaces are used correctly.
> Allow for non-string keys
> -------------------------
>
> Key: AVRO-680
> URL: https://issues.apache.org/jira/browse/AVRO-680
> Project: Avro
> Issue Type: Improvement
> Affects Versions: 1.7.6, 1.7.7
> Reporter: Jeremy Hanna
> Attachments: AVRO-680.patch, non_string_map_keys.zip,
> non_string_map_keys2.zip, non_string_map_keys3.zip
>
>
> Based on an email thread back in April, Doug Cutting proposed a possible
> solution for having non-string keys:
> Stu Hood wrote:
> > I can understand the reasoning behind AVRO-9, but now I need to look for an
> > alternative to a 'map' that will allow me to store an association of bytes
> > keys to values.
> A map of Foo has the same binary format as an array of records, each
> with a string field and a Foo field. So an application can use an array
> schema similar to this to represent map-like structures with, e.g.,
> non-string keys.
> Perhaps we could establish standard properties that indicate that a
> given array of records should be represented in a map-like way if
> possible? E.g.,:
> {"type": "array", "isMap": true, "items": {"type":"record", ...}}
> Doug
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