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From "Xuefu Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-7049) Unable to deserialize AVRO data when file schema and record schema are different and nullable
Date Tue, 13 May 2014 17:24:14 GMT

    [ https://issues.apache.org/jira/browse/HIVE-7049?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13996660#comment-13996660
] 

Xuefu Zhang commented on HIVE-7049:
-----------------------------------

Thanks for bringing this up.  I'm wondering if the situation you described is an issue of
incompatibility of schemas rather than a bug. Record schema says that a field is union (nullable),
while file schema says that the file is not a union, which seems suggesting that the data
is not compatible with the schema. While we may need to provided a better error message for
this, ignoring the file schema (by passing NULL down) will very likely break decimal support,
which needs the file schema to read data correctly.

> Unable to deserialize AVRO data when file schema and record schema are different and
nullable
> ---------------------------------------------------------------------------------------------
>
>                 Key: HIVE-7049
>                 URL: https://issues.apache.org/jira/browse/HIVE-7049
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Mohammad Kamrul Islam
>            Assignee: Mohammad Kamrul Islam
>         Attachments: HIVE-7049.1.patch
>
>
> It mainly happens when 
> 1 )file schema and record schema are not same
> 2 ) Record schema is nullable  but file schema is not.
> The potential code location is at class AvroDeserialize
>  
> {noformat}
>  if(AvroSerdeUtils.isNullableType(recordSchema)) {
>       return deserializeNullableUnion(datum, fileSchema, recordSchema, columnType);
>     }
> {noformat}
> In the above code snippet, recordSchema is verified if it is nullable. But the file schema
is not checked.
> I tested with these values:
> {noformat}
> recordSchema= ["null","string"]
> fielSchema= "string"
> {noformat}
> And i got the following exception <line numbers might not be the same due to mu debugged
code version>.
> {noformat}
> org.apache.avro.AvroRuntimeException: Not a union: "string" 
>         at org.apache.avro.Schema.getTypes(Schema.java:272)
>         at org.apache.hadoop.hive.serde2.avro.AvroDeserializer.deserializeNullableUnion(AvroDeserializer.java:275)
>         at org.apache.hadoop.hive.serde2.avro.AvroDeserializer.worker(AvroDeserializer.java:205)
>         at org.apache.hadoop.hive.serde2.avro.AvroDeserializer.workerBase(AvroDeserializer.java:188)
>         at org.apache.hadoop.hive.serde2.avro.AvroDeserializer.deserialize(AvroDeserializer.java:174)
>         at org.apache.hadoop.hive.serde2.avro.TestAvroDeserializer.verifyNullableType(TestAvroDeserializer.java:487)
>         at org.apache.hadoop.hive.serde2.avro.TestAvroDeserializer.canDeserializeNullableTypes(TestAvroDeserializer.java:407)
> {noformat}



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