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From "Dylan Hutchison (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-3206) New Public API: Approximate data counts of Tablets and Tablet Servers
Date Sun, 05 Oct 2014 20:02:34 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-3206?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14159662#comment-14159662
] 

Dylan Hutchison commented on ACCUMULO-3206:
-------------------------------------------

If ACCUMULO-3005 goes through, additional programmatic access to metrics is just a convenience.
 The client could request info from the Monitor instead of the Master, though the Monitor
almost always shares the same host as the Master.  From what I can tell ACCUMULO-3005 promises
both HTTP for a nice web layout of the DB status and, more relevantly to this issue, JSON
for "just the data please" access to specific metrics.  Hey, for that matter, we could imagine
taking all Accumulo operations and requests that do not require authentication to the Monitor
web server.

> New Public API: Approximate data counts of Tablets and Tablet Servers
> ---------------------------------------------------------------------
>
>                 Key: ACCUMULO-3206
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-3206
>             Project: Accumulo
>          Issue Type: New Feature
>          Components: client, monitor
>    Affects Versions: 1.6.1
>            Reporter: Dylan Hutchison
>            Priority: Minor
>             Fix For: 1.7.0
>
>
> The broader picture is public programmatic access to information in the Accumulo monitor.
 Specifically I'm looking to obtain the number of entries per tablet and per tablet server
for a given table.  The use case is to verify that manually set (or automatically set I suppose)
table splits are effectively dividing Accumulo data among many tablets, that is, verifying
load balancing.
> I wrote Accumulo 1.5 code which uses non-public API to obtain this information in the
same way the Monitor does via TabletStats. The tricky part was cross-referencing the Metadata
table to find the assignment of tablets to tablet servers for a given table.  I rewrote that
code for 1.6, switching the name of the Metadata table to "accumulo.metadata" and other associated
changes, but it would be great to make this part of the public API so that people don't have
to use non-public methods to obtain data that Accumulo has in the Monitor and Metadata table
anyway.
> We could approach this by adding to the TableOperations class or something similar. 
A request could go to an Accumulo master which gathers the necessary information from the
tablet servers just as the Monitor does, so that the client does not have to do it.



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