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From "Zheng Shao (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HIVE-699) Make lots of existing ObjectInspectors settable
Date Wed, 29 Jul 2009 08:12:14 GMT

     [ https://issues.apache.org/jira/browse/HIVE-699?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Zheng Shao updated HIVE-699:
----------------------------

    Attachment: HIVE-699.1.patch

This patch does the trick. As a side effect, UDAF can take complex arguments and return complex
values - Hive will convert the object to the corresponding Java Class on the fly.

This patch also includes an example UDAF (average) that uses a static inner class with 2 fields:
mCount and mSum to store the internal state.  The terminatePartial function just returns an
object of this inner class, and Hive is capable of reading the value out using reflection
ObjectInspector. Then in the reducer, Hive converts a struct with these 2 fields into an object
of this inner class by using the ReflectionStructObjectInspector(which implements SettableStructObjectInspector).


> Make lots of existing ObjectInspectors settable
> -----------------------------------------------
>
>                 Key: HIVE-699
>                 URL: https://issues.apache.org/jira/browse/HIVE-699
>             Project: Hadoop Hive
>          Issue Type: Improvement
>            Reporter: Zheng Shao
>            Assignee: Zheng Shao
>         Attachments: HIVE-699.1.patch
>
>
> We should make JavaObjectInspectors, StandardList/Struct/MapObjectInspector, ReflectionObjectInspectors
settable.
> This will allow us to make it possible to *write* into Thrift tables, as well as ProtocolBuffer
tables in the future.
> This will also allow us to pass complex objects into UDF and receive complex objects
from UDF by using ObjectInspectorConverters.

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