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From Ara Ebrahimi <ara.ebrah...@argyledata.com>
Subject Re: OfflineScanner
Date Thu, 19 Feb 2015 21:07:45 GMT
Actually I was wrong. OfflineScanner is public, OfflineIterator is package. So it’s good
enough :)

Ara.

> On Feb 19, 2015, at 11:46 AM, Josh Elser <josh.elser@gmail.com> wrote:
>
> Want to file a ticket, Ara? I didn't realize it wasn't directly in the
> public API (only via m/r). I think it would make a nice addition.
>
> Ara Ebrahimi wrote:
>> OfflineScanner is package protected. So I'll need to hack it. If it
>> proves to be faster at least 20% then it's worth having it in the public
>> Ali, perhaps even let user use it by a asking specific file to be
>> scanned rather than directing scan by carefully defining the range to
>> touch the intended file.
>>
>> Ara.
>>
>> On Feb 19, 2015, at 8:15 AM, Keith Turner <keith@deenlo.com
>> <mailto:keith@deenlo.com>> wrote:
>>
>>>
>>>
>>> On Thu, Feb 19, 2015 at 12:57 AM, Ara Ebrahimi
>>> <ara.ebrahimi@argyledata.com <mailto:ara.ebrahimi@argyledata.com>>
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?
>>>
>>>
>>> The code will throw an exception if the table is not offline (intent
>>> is to ensure the files are stable and not garbage collected). As
>>> others have stated you can clone.
>>> Currently offline scanning is only supported in the public API w/ Map
>>> Reduce. Curious, would you be interested in seeing this in the client
>>> public API?
>>>
>>>
>>>    Thanks,
>>>    Ara.
>>>
>>>
>>>
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>>
>>
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>
>
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This message is for the designated recipient only and may contain privileged, proprietary,
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sender immediately and delete the original. Any other use of the e-mail by you is prohibited.
Thank you in advance for your cooperation.

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