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From "Rich Fecher (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-2883) Add API method(s) that support fetching currently assigned locations for tablets
Date Wed, 19 Nov 2014 22:56:35 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-2883?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14218657#comment-14218657
] 

Rich Fecher commented on ACCUMULO-2883:
---------------------------------------

If it would help to understand a third-party use case, we ran into this need of a tablet locator
as part of the public API.  We had needed an input format that behaves significantly differently
from Accumulo's public API input format (ie. inheritance or delegation would not suffice in
our case) but it was still very important to us to try to co-locate processing.  So to attempt
to co-locate with the tablets, we used the TabletLocator and frankly a snippet of code very
similar to the internals of Accumulo's input format (https://github.com/ngageoint/geowave/blob/master/geowave-accumulo/src/main/java/mil/nga/giat/geowave/accumulo/mapreduce/input/GeoWaveInputFormat.java#L410)

However, to support changes between 1.5.1 and 1.6.0 we ended up using conditional compilation
provided by the maven munge plugin.  This is less than ideal and are looking forward to hooks
in the public API for this.

> Add API method(s) that support fetching currently assigned locations for tablets
> --------------------------------------------------------------------------------
>
>                 Key: ACCUMULO-2883
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-2883
>             Project: Accumulo
>          Issue Type: Sub-task
>          Components: client
>            Reporter: Josh Elser
>             Fix For: 1.7.0
>
>
> TabletLocator already exists, but isn't officially a part of the "public API" and is
clunky for users to invoke. In trying to co-locate external processes with the tabletservers
that are hosting some data, it would be nice to have some means that users can invoke that
will return them these assignments.
> Memory concerns are an issue for tables with many splits (e.g. avoiding creating a Set
of 100k tablet locations for a table), but we also want to provide the ability to ask pointed
questions. Likely building something that accepts a Range (or Collection<Range>) would
be best.



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