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Date: Mon, 28 Aug 2017 17:26:00 +0000 (UTC)
From: "Ratandeep Ratti (JIRA)" <jira@apache.org>
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Subject: [jira] [Updated] (HIVE-17394) AvroSerde is regenerating TypeInfo
 objects for each nullable Avro field for every row
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archived-at: Mon, 28 Aug 2017 17:26:07 -0000


     [ https://issues.apache.org/jira/browse/HIVE-17394?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ratandeep Ratti updated HIVE-17394:
-----------------------------------
    Attachment: AvroSerDeUnionTypeInfo.png
                AvroSerDe.nps

> AvroSerde is regenerating TypeInfo objects for each nullable Avro field for every row
> -------------------------------------------------------------------------------------
>
>                 Key: HIVE-17394
>                 URL: https://issues.apache.org/jira/browse/HIVE-17394
>             Project: Hive
>          Issue Type: Bug
>    Affects Versions: 1.1.0
>            Reporter: Ratandeep Ratti
>         Attachments: AvroSerDe.nps, AvroSerDeUnionTypeInfo.png
>
>
> The following methods in {{AvroDeserializer}} keep regenerating TypeInfo objects for every nullable  field in a row.
> This is happening in the following methods.
> {code}
> private Object deserializeNullableUnion(Object datum, Schema fileSchema, Schema recordSchema) throws AvroSerdeException {
> // elided
> line 312:  return worker(datum, fileSchema, newRecordSchema,
>             SchemaToTypeInfo.generateTypeInfo(newRecordSchema, null));
> }
> ..
> private Object deserializeSingleItemNullableUnion(Object datum, Schema Schema recordSchema)
> // elided
> line 357: return worker(datum, currentFileSchema, schema,
>       SchemaToTypeInfo.generateTypeInfo(schema, null));
> {code}
> This is really bad in terms of performance. I'm not sure why didn't we use the TypeInfo we already have instead of generating again for each nullable field.  If you look at the {{worker}} method which calls the method {{deserializeNullableUnion}} the typeInfo corresponding to the nullable field column is already determined. Not sure why we have to determine that information again.
> More the cache in SchmaToTypeInfo does not help in nullable Avro records case as checking if an Avro record schema object already exists in the cache requires traversing the all the fields in the record schema.
> I've attached profiling snapshot which shows maximum time is being spent in the cache.
> One way of fixing this IMO is to make use of the column TypeInfo which is already passed in the worker method.


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