So, the initial input stream is decompressed, then each temporary file gets
compressed and decompressed, and the avro output is then recompressed,
decompressed again at the reducers?
I'm counting 2 compressions and 2 decompressions at the mappers and 1
decompression at the reducers.
Am I getting this right?
- Tim.
________________________________________
From: Arun C Murthy [[email protected]]
Sent: Thursday, January 12, 2012 3:15 PM
To: [email protected]
Subject: Re: Can spill to disk be in compressed format to reduce I/O?
Temporary map-ouput files don't use Avro format. There is a custom format which
should be compressed if you set mapred.compress.map.output.
Arun
On Jan 12, 2012, at 8:08 AM, Frank Grimes wrote:
> I tried conf.setBoolean("mapred.compress.map.output", true); but it didn't
> seem to work.
>
> Also, since I'm using the Avro mapred APIs, maybe there's something Avro
> specific to get it enabled?
> Should I ask on the Avro mailing lists?
>
> Thanks,
>
> Frank Grimes
>
>
> On 2012-01-12, at 10:49 AM, [email protected] wrote:
>
>> Hi Frank
>> Is map output compression enabled?
>>
>> The config param would be like
>> mapred.map.output.compress=true
>> (It is from my memory, Please cross check)
>>
>> ------Original Message------
>> From: Frank Grimes
>> To: [email protected]
>> ReplyTo: [email protected]
>> Subject: Can spill to disk be in compressed format to reduce I/O?
>> Sent: Jan 12, 2012 21:10
>>
>> Hi All,
>>
>> We're trying to speed up an M/R job which combines multiple .avro files.
>> We've noticed that when it spills to disk, it's in uncompressed format.
>> Is there a way to make it spill temporary segments as .avro with Deflate
>> compression?
>>
>> Thanks,
>>
>> Frank Grimes
>>
>> Regards
>> Bejoy K S
>
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