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From tim robertson <timrobertson...@gmail.com>
Subject Re: Splittable lzo files
Date Tue, 03 Mar 2009 08:43:46 GMT
Thanks for posting this Johan,

I tried unsuccessfully to handle GZip files for the reasons you state
and resorted to uncompressed.  I will try the Lzo format and post the
performance difference of compressed vs uncompressed on EC2 which
seems to have very slow disk IO.  We have seen really bad import
speeds (like worse than mini macs even with the largest instances) on
postgis and mysql with EC2 so I think this might be very applicable to
the EC2 users.

Cheers,

Tim




On Tue, Mar 3, 2009 at 9:32 AM, Johan Oskarsson <johan@oskarsson.nu> wrote:
> Hi,
>
> thought I'd pass on this blog post I just wrote about how we compress our
> raw log data in Hadoop using Lzo at Last.fm.
>
> The essence of the post is that we're able to make them splittable by
> indexing where each compressed chunk starts in the file, similar to the gzip
> input format being worked on.
> This actually gives us a performance boost in certain jobs that read a lot
> of data while saving us disk space at the same time.
>
> http://blog.oskarsson.nu/2009/03/hadoop-feat-lzo-save-disk-space-and.html
>
> /Johan
>

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