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From Deepak Majeti <majeti.dee...@gmail.com>
Subject Re: ORC magic
Date Fri, 15 Dec 2017 15:00:14 GMT
Hi Xiening,

The readers (both java and c++) just use the "magic" bits present in the
Tail to verify ORC files. But the spec requires "ORC" bits to be present in
the header as well to support tools that scan from the front.
You can verify this from the ORC files written by the Java writer.
I just observed this requirement today as well. We should support this with
the C++ writer too if we don't already.


On Fri, Dec 15, 2017 at 2:45 AM, Dain Sundstrom <dain@iq80.com> wrote:

> Thanks Deepak. I was searching for “magic” and missed this part.
>
> -dain
>
> > On Dec 14, 2017, at 7:16 PM, Deepak Majeti <majeti.deepak@gmail.com>
> wrote:
> >
> > Hi Dain,
> >
> > The ORC spec requires that a file start with "ORC".
> >
> > From https://orc.apache.org/docs/file-tail.html
> >
> > "The file is broken in to three parts- Header, Body, and Tail. The Header
> > consists of the bytes “ORC’’ to support tools that want to scan the front
> > of the file to determine the type of the file."
> >
> > On Thu, Dec 14, 2017 at 2:00 PM, Dain Sundstrom <dain@iq80.com> wrote:
> >
> >> Does the ORC spec require that a file start with “ORC”?
> >>
> >> -dain
> >
> >
> >
> >
> > --
> > regards,
> > Deepak Majeti
>
>


-- 
regards,
Deepak Majeti

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