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From "David Medinets (JIRA)" <>
Subject [jira] [Updated] (ACCUMULO-132) read-only access to existing tables for speculative execution
Date Sat, 19 Apr 2014 21:09:14 GMT


David Medinets updated ACCUMULO-132:

    Priority: Minor  (was: Major)

891 days since the last comment.

> read-only access to existing tables for speculative execution
> -------------------------------------------------------------
>                 Key: ACCUMULO-132
>                 URL:
>             Project: Accumulo
>          Issue Type: New Feature
>          Components: client
>            Reporter: Eric Newton
>            Priority: Minor
> An accumulo user has a need to perform a map/reduce over an entire table.   Right now,
if a tablet server is running on a machine that has become slow due to failing hardware (it
happens... a lot), the mapper using that server also runs slowly.  If we allow speculative
execution, the second map just goes back to the same tablet server, doubling the load on our
already slow server.  However, the data behind the tablet server is sitting there in multiple
locations in HDFS.  The user can live without pulling the most recent updates in the tablet
server's memory.
> Possible solutions:
>  # provide read-only hosting of a tablet from another node, possibly on demand
>  # convenient way of re-creating the tablet server iterator stack and reading the files
>  # clone the table/tablet (has the benefit that a reference is maintained in the metadata

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