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From Alparslan Avcı (JIRA) <j...@apache.org>
Subject [jira] [Commented] (GORA-401) Serialization and deserialization of Persistent does not hold the entity dirty state
Date Wed, 14 Jan 2015 15:48:35 GMT

    [ https://issues.apache.org/jira/browse/GORA-401?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14277098#comment-14277098
] 

Alparslan Avcı commented on GORA-401:
-------------------------------------

Yes, this is a bug and caused of since we removed the {{_g_dirty}} field from the persistent
object's schema. After GORA-326, {{_g_dirty}} field is moved to {{PersistentBase}} and also
removed from the schema, but Avro uses persistent object's schema to serialize and deserialize
objects in {{GenericDatumWriter}} and {{GenericDatumReader}}. Thus, after serializing and
deserializing an object we lose the dirtyness info.

> 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
>            Priority: Critical
>              Labels: serialization
>         Attachments: GORA-401-tests.patch
>
>   Original Estimate: 35h
>  Remaining Estimate: 35h
>
> 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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