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Hadoop >> mail # user >> Re: Should splittable Gzip be a "core" hadoop feature?


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Re: Should splittable Gzip be a "core" hadoop feature?
I can see a use for it, but I have two concerns about it.  My biggest concern is maintainability.  We have had lots of things get thrown into contrib in the past, very few people use them, and inevitably they start to suffer from bit rot.  I am not saying that it will happen with this, but if you have to ask if people will use it and there has been no overwhelming yes, it makes me nervous about it.  My second concern is with knowing when to use this.  Anything that adds this in would have to come with plenty of documentation about how it works, how it is different from the normal gzip format, explanations about what type of a load it might put on data nodes that hold the start of the file, etc.

>From both of these I would prefer to see this as a github project for a while first, and one it shows that it has a significant following, or a community with it, then we can pull it in.  But if others disagree I am not going to block it.  I am a -0 on pulling this in now.

--Bobby

On 2/29/12 10:00 AM, "Niels Basjes" <[EMAIL PROTECTED]> wrote:

Hi,

On Wed, Feb 29, 2012 at 16:52, Edward Capriolo <[EMAIL PROTECTED]>wrote:
...

> But being able to generate split info for them and processing them
> would be good as well. I remember that was a hot thing to do with lzo
> back in the day. The pain of once overing the gz files to generate the
> split info is detracting but it is nice to know it is there if you
> want it.
>

Note that the solution I created (HADOOP-7076) does not require any
preprocessing.
It can split ANY gzipped file as-is.
The downside is that this effectively costs some additional performance
because the task has to decompress the first part of the file that is to be
discarded.

The other two ways of splitting gzipped files either require
- creating come kind of "compression index" before actually using the file
(HADOOP-6153)
- creating a file in a format that is gerenated in such a way that it is
really a set of concatenated gzipped files. (HADOOP-7909)

--
Best regards / Met vriendelijke groeten,

Niels Basjes