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From Marc Reichman <>
Subject Re: OfflineScanner
Date Thu, 19 Feb 2015 15:47:30 GMT
Apologies for hijacking this, but is there any way to use an offline table
clone with MapReduce and AccumuloInputFormat? That read speed increase
sounds very appealing..

On Thu, Feb 19, 2015 at 9:27 AM, Josh Elser <> wrote:

> Typically, if you're using the OfflineScanner, you'd clone the table you
> want to read and then take the clone offline. It's a simple (and fast)
> solution that doesn't interrupt the availability of the table.
> Doing the read offline will definitely be faster (maybe 20%, I'm not
> entirely sure on accurate number and how it scales with nodes). The pain
> would be the extra work in creating the clone, offline'ing the table, and
> eventually deleting the clone when you're done with it. A little more work,
> but manageable.
> Ara Ebrahimi wrote:
>> Hi,
>> I’m trying to optimize a connector we’ve written for Presto. In some
>> cases we need to perform full table scans. This happens across all the
>> nodes but each node is assigned to process only a sharded subset of data.
>> Each shard is hosted by only 1 RFile. I’m looking at the
>> AbstractInputFormat and OfflineIterator and it seems like the code is not
>> that hard to use for this case. Is there any drawback? It seems like if the
>> table is offline then OfflineIterator is used which apparently reads the
>> RFiles directly and doesn’t involve any RPC and I think should be
>> significantly faster. Is it so? Is there any drawback to using this while
>> the table is not offline but no other app is messing with the table?
>> Thanks,
>> Ara.
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