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From "Kevin Ratnasekera (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (GORA-401) Serialization and deserialization of Persistent does not hold the entity dirty state from Map to Reduce
Date Mon, 19 Sep 2016 06:51:22 GMT

    [ https://issues.apache.org/jira/browse/GORA-401?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15502509#comment-15502509
] 

Kevin Ratnasekera commented on GORA-401:
----------------------------------------

[~alfonso.nishikawa] Thanks for review and comments :). Even though we have two approaches
here, the idea behind is exactly the same. I have tested your test cases against the fix.
Those HBase test case passes successfully when the fix is present. I did even debug manually
the test case written, and noticed that dirty state of persistent bean is correctly maintained
between map and reduce methods MR job before writing to context. That guarantee dirty data
bean get successfully written to  out dataStore when we write to context.

I have update my PR against your HBase test case provided here with patch. I also think this
should work perfectly fine with other dataStores other than HBase as well.

Regards
Kevin 

> Serialization and deserialization of Persistent does not hold the entity dirty state
from Map to Reduce
> -------------------------------------------------------------------------------------------------------
>
>                 Key: GORA-401
>                 URL: https://issues.apache.org/jira/browse/GORA-401
>             Project: Apache Gora
>          Issue Type: Bug
>          Components: gora-core
>    Affects Versions: 0.4, 0.5
>         Environment: Tested on gora-0.4, but seems logically to hold on gora-0.5. HBase
backend.
>            Reporter: Alfonso Nishikawa
>            Assignee: Alfonso Nishikawa
>            Priority: Critical
>              Labels: serialization
>             Fix For: 0.8
>
>         Attachments: GORA-401-tests.patch, GORA-401v1.patch, GORA-401v2.patch, GORA-401v3.patch,
GORA-401v4.patch, GORA-401v5.patch
>
>   Original Estimate: 35h
>          Time Spent: 21h
>  Remaining Estimate: 14h
>
> After removing __g__dirty field in GORA-326, dirty field is not serialized. In GORA-321
{{[PersistentSerializer|https://github.com/apache/gora/blob/master/gora-core/src/main/java/org/apache/gora/mapreduce/PersistentSerializer.java]}}
went from using {{[PersistentDatumWriter|https://github.com/apache/gora/blob/apache-gora-0.3/gora-core/src/main/java/org/apache/gora/avro/PersistentDatumWriter.java](/Reader)}}
to Avro's {{SpecificDatumWriter}}, delegating the serialization of the dirty field to Avro
(but really not desirable to have that field as a main field in the entities).
> The proposal is to reintroduce the {{PersistentDatumWriter/Reader}} which will serialize
the internal fields of the entities.
> This bug affects, for example, Nutch, which loads only some fields in it's phases, serializes
entities (from Map to Reduce), and when deserializes finds all fields as "dirty", independently
of what fields were modified in the Map, and overwrite all data in datastore (deleting much
things: downloaded content, parsed content, etc).
> This effect can be seen in {{TestPersistentSerialization#testSerderEmployeeTwoFields}},
when debuging in {{TestIOUtils#testSerializeDeserialize}}. Proper breakpoints an inspections
shows that, entities are "equal" when it's fields are equal. This is fine as "equal" definition,
but another test must be added to check that serialization an deserialization keeps the dirty
state.



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