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From Jean-Daniel Cryans <jdcry...@apache.org>
Subject Re: read short circuit
Date Thu, 13 Sep 2012 16:51:07 GMT
On Thu, Sep 13, 2012 at 9:42 AM, n keywal <nkeywal@gmail.com> wrote:
> It's all in the "pretty much" :-)
> Should we make it the default (i.e. recommending it in the doc, emitting a
> warning if it's not set) for all installation ?

I'd recommend it in the doc as an important config to consider.

One issue with the current implementation is that you can only have 1
user that short circuit reads, all the others who have the config
enabled will get a fat Exception. At SU we don't have special config
files for every MR job so unless you disable it job by job then you'll
get those exceptions everywhere. We live with it but it did take
people by surprise when we rolled it out :)

> Or would it make sense to separate the store and wal cases, meaning that we
> need a change in hdfs to make this possible?

Don't we only have one FS instance per region server? If so, that's a
moot point.


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