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From "Alfonso Nishikawa (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (GORA-401) Serialization and deserialization of Persistent does not hold the entity dirty state from Map to Reduce
Date Mon, 09 Feb 2015 16:38:35 GMT

    [ https://issues.apache.org/jira/browse/GORA-401?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14312427#comment-14312427
] 

Alfonso Nishikawa edited comment on GORA-401 at 2/9/15 4:37 PM:
----------------------------------------------------------------

@[~hsaputra], AvroStore uses SpecificDatumWriter [1] when persisting (as [~renato2099] argued).
Anyway, even using PersistentDatumWriter, _I think_ it writes all data as a hole in binary/JSON
not just updating fields. If I am not wrong, what I saw is that AvroStore just writes appending
to a file (unable to update) [2].

I think there are more issues with AvroStore, like the need to close it to get all data written
to disk (at least I was having some troubles reading data when the AvroStore was not previously
closed).
I don't feel comfortable about having to modify excessively the behavior of AvroStore to get
the tests passed.

Thanks!

[1] - https://github.com/apache/gora/blob/master/gora-core/src/main/java/org/apache/gora/avro/store/AvroStore.java#L238
[2] - https://github.com/apache/gora/blob/master/gora-core/src/main/java/org/apache/gora/avro/store/AvroStore.java#L183


was (Author: alfonso.nishikawa):
@[~hsaputra], AvroStore uses SpecificDatumWriter [1] when persisting (as [~renato2099] argued).
Anyway, even using PersistentDatumWriter, _I think_ it writes all data as a hole in binary/JSON
not just updating fields. If I am not wrong, what I saw is that AvroStore just writes appending
to a file (unable to update) [2].

I think there are more issues with AvroStore, like the need to close it to get all data written
to disk (at least I was having some troubles reading data when the AvroStore was not previously
closed).
I don't feel comfortable about having to modify excessively the behavior of AvroStore to get
the tests passed.

[1] - https://github.com/apache/gora/blob/master/gora-core/src/main/java/org/apache/gora/avro/store/AvroStore.java#L238
[2] - https://github.com/apache/gora/blob/master/gora-core/src/main/java/org/apache/gora/avro/store/AvroStore.java#L183

> 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: 0.7
>
>         Attachments: GORA-401-tests.patch, GORA-401v1.patch, GORA-401v2.patch, GORA-401v3.patch,
GORA-401v4.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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