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From Rasit OZDAS <rasitoz...@gmail.com>
Subject Re: HELP: I wanna store the output value into a list not write to the disk
Date Thu, 02 Apr 2009 15:21:07 GMT
Andy, I didn't try this feature. But I know that Yahoo had a
performance record with this file format.
I came across a file system included in hadoop code (probably that
one) when searching the source code.
Luckily I found it: org.apache.hadoop.fs.InMemoryFileSystem
But if you have a lot of big files, this approach won't be suitable I think.

Maybe someone can give further info.

2009/4/2 andy2005cst <andy2005cst@gmail.com>:
>
> thanks for your reply. Let me explain more clearly, since Map Reduce is just
> one step of my program, I need to use the output of reduce for furture
> computation, so i do not need to want to wirte the output into disk, but
> wanna to get the collection or list of the output in RAM. if it directly
> wirtes into disk, I have to read it back into RAM again.
> you have mentioned a special file format, will you please show me what is
> it? and give some example if possible.
>
> thank you so much.
>
>
> Rasit OZDAS wrote:
>>
>> Hi, hadoop is normally designed to write to disk. There are a special file
>> format, which writes output to RAM instead of disk.
>> But I don't have an idea if it's what you're looking for.
>> If what you said exists, there should be a mechanism which sends output as
>> objects rather than file content across computers, as far as I know there
>> is
>> no such feature yet.
>>
>> Good luck.
>>
>> 2009/4/2 andy2005cst <andy2005cst@gmail.com>
>>
>>>
>>> I need to use the output of the reduce, but I don't know how to do.
>>> use the wordcount program as an example if i want to collect the
>>> wordcount
>>> into a hashtable for further use, how can i do?
>>> the example just show how to let the result onto disk.
>>> myemail is : andy2005cst@gmail.com
>>> looking forward your help. thanks a lot.
>>> --
>>> View this message in context:
>>> http://www.nabble.com/HELP%3A-I-wanna-store-the-output-value-into-a-list-not-write-to-the-disk-tp22844277p22844277.html
>>> Sent from the Hadoop core-user mailing list archive at Nabble.com.
>>>
>>>
>>
>>
>> --
>> M. Raşit ÖZDAŞ
>>
>>
>
> --
> View this message in context: http://www.nabble.com/HELP%3A-I-wanna-store-the-output-value-into-a-list-not-write-to-the-disk-tp22844277p22848070.html
> Sent from the Hadoop core-user mailing list archive at Nabble.com.
>
>



-- 
M. Raşit ÖZDAŞ

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