[jira] [Commented] (AVRO-1827) Handling correctly optional fields when converting Protobuf to Avro

["Karel Fuka (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/AVRO-1827?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16241848#comment-16241848 ] 

Karel Fuka commented on AVRO-1827:
----------------------------------

Hi [~busbey], please let me know if we can help here to get this moving. Thanks 



> Handling correctly optional fields when converting Protobuf to Avro
> -------------------------------------------------------------------
>
>                 Key: AVRO-1827
>                 URL: https://issues.apache.org/jira/browse/AVRO-1827
>             Project: Avro
>          Issue Type: Improvement
>    Affects Versions: 1.7.7, 1.8.0
>            Reporter: Jakub Kahovec
>            Assignee: Karel Fuka
>         Attachments: AVRO-1827.patch, AVRO-1827.patch, AVRO-1827.patch, AVRO-1827.patch
>
>
> Hello,
> as of the current implementation of converting protobuf files into avro format, protobuf optional fields are being  given default values in the avro schema if not specified explicitly. 
> So for instance when the protobuf field is defined as  
> {quote}
> optional int64 fieldInt64 = 1;
> {quote}
> in the avro schema it appears as
> {quote}
>  "name" : "fieldInt64",
>   "type" : "long",
>   "default" : 0
> {quote}
> The problem with this implementation is that we are losing information about whether the field was present or not in the original protobuf, as when we ask for this field's value in avro we will be given the default value. 
> What I'm proposing instead is that if the field in the protobuf is defined as optional and has no default value then the generated avro schema type will us a union comprising the matching type and null type with default value null. It is going to look like this:
> {quote}
>  "name" : "fieldIn64",
>   "type" : [ "null", "long" ],
>   "default" : null
> {quote}
> I'm aware that is a breaking change but I think that is the proper way how to handle optional fields.
> I've also  created a patch which fixes the conversion
> Jakub 



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