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From "Keith Turner (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-4062) Change MutationSet.mutations to use HashSet
Date Fri, 20 Nov 2015 17:06:11 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-4062?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15018341#comment-15018341
] 

Keith Turner commented on ACCUMULO-4062:
----------------------------------------

Personally, I think the issue of deduping the same col+values in different order that Josh
brought up is a good reason not to do it.  Because I think handling this case properly would
be expensive.   Maybe its cheap if we do not worry about that case, but since its a half solution
user concerned about this still may have to dedupe outside the batchwriter.

Could do something like the way java streams work e.g. {{new ZipOutputStream(new FileOutputStream())}}.
 One possibility is that we create a DedupingBatchWriter that wraps a BatchWriter like {{new
DedupingBatchWriter(batchWriter, options)}}.  

Also Mutations are not usually used as a key in Accumulo code. Most code just keys on the
mutations row.  The Mutations hashcode and equals functions would need a good set of unit
test added if something in Accumulo were going to rely on them.

> Change MutationSet.mutations to use HashSet
> -------------------------------------------
>
>                 Key: ACCUMULO-4062
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-4062
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: client
>            Reporter: Dave Marion
>
> Change TabletServerBatchWriter.MutationSet.mutations from a
> {code}
>   HashMap<String,List<Mutation>>
> {code}
> to
> {code}
>   HashMap<String,HashSet<Mutation>>
> {code}
> so that duplicate mutations added by a client are not sent to the server.



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