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From Jan Holmberg <jan.holmb...@perigeum.fi>
Subject Re: Max number of columns
Date Mon, 19 Jun 2017 05:30:58 GMT
Thanks for the answer. I'm bit surprised about this. Sure I understand that there's some upper
limit but 300 seems pretty low value. Support for wider tables if definitively required in
analytical use cases. Hopefully someone starts working on this.


On 18 Jun 2017, at 23.22, Todd Lipcon <todd@cloudera.com<mailto:todd@cloudera.com>>

Hi Jan,

I don't believe anyone is currently working on expanding the limitation.

If you are willing to live on the edge, it is possible to use --unlock-unsafe-flags and bump
the limit to a higher number. However, you may run into performance or stability issues, since
you are entering a realm of usage that has no testing or real world usage, so if you do hit
an issue, you'll probably be on your own to diagnose and debug the problem.

There are a few things in flight (eg Hao is working on reducing the number of fsyncs when
writing blocks) which may help the issue, but until we've expanded testing coverage, we don't
want to recommend users operate past these limits.


On Sun, Jun 18, 2017 at 12:35 PM, Jan Holmberg <jan.holmberg@perigeum.fi<mailto:jan.holmberg@perigeum.fi>>
Anyone? I find 300 columns pretty strict limitation for analytical tables. I'd liked to know
if wider tables are on the roadmap.


> On 16 Jun 2017, at 21.56, Jan Holmberg <jan.holmberg@perigeum.fi<mailto:jan.holmberg@perigeum.fi>>
> Hi,
> I ran into Kudu limitation of max columns (300). Same limit seemed to apply latest Kudu
version as well but not ex. Impala/Hive (in the same extent at least).
> * is this limitation going to be loosened in near future?
> * any suggestions how to get over this limitation? Table splitting is the obvious one
but in my case not the desired solution.
> cheers,
> -jan

Todd Lipcon
Software Engineer, Cloudera

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