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From Renato Javier Marroquín Mogrovejo (JIRA) <j...@apache.org>
Subject [jira] [Commented] (GORA-401) Serialization and deserialization of Persistent does not hold the entity dirty state
Date Sat, 17 Jan 2015 13:11:35 GMT

    [ https://issues.apache.org/jira/browse/GORA-401?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14281338#comment-14281338
] 

Renato Javier Marroquín Mogrovejo commented on GORA-401:
--------------------------------------------------------

Hi [~alparslan.avci], yes, I misinterpreted [~alfonso.nishikawa]'s ultimate purpose. I think
we can add the feature of passing dirty bits between two processes that don't share the same
JVM, but we should do it in another JIRA or change the name of this one because it is, IMHO,
very misleading. I also don't agree with putting PersistentDatumReader/Writer back in just
to have this feature. Maybe a good starting point would be [1], and providing a way for users
to configure from GoraInputFormat. I don't know how this was configure before, do you guys
know?

[1] https://github.com/apache/gora/blob/master/gora-core/src/main/java/org/apache/gora/mapreduce/PersistentSerializer.java

> Serialization and deserialization of Persistent does not hold the entity dirty state
> ------------------------------------------------------------------------------------
>
>                 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
>         Attachments: GORA-401-tests.patch
>
>   Original Estimate: 35h
>          Time Spent: 6.5h
>  Remaining Estimate: 28.5h
>
> 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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