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Hive >> mail # user >> Re: getStructFieldData method on StructObjectInspector


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Re: getStructFieldData method on StructObjectInspector
Thanks Edward for your reply on this.

Would you mind giving a very small example on how a struct corresponds to a
Map? I am having hard time understanding what the K/V pairs in the map
would look like.

Thanks again.

On Tue, May 29, 2012 at 10:16 AM, Edward Capriolo <[EMAIL PROTECTED]>wrote:

> Returning custom writables will not work. In most cases the methods
> return Object because the types can be many things that do not fall
> under a single superclass other then object. like Integer,IntWritable,
> Array<IntWritable>, or Map. In your case, a struct corresponds to a
> Map.
>
> On Tue, May 29, 2012 at 11:08 AM, [EMAIL PROTECTED]
> <[EMAIL PROTECTED]> wrote:
> > If someone can help understand this, I would really appreciate.
> >
> > On Fri, May 25, 2012 at 3:58 PM, [EMAIL PROTECTED]
> > <[EMAIL PROTECTED]> wrote:
> >>
> >> I am trying to write a custom ObjectInspector extending the
> >> StructObjectInspector and got a little confused about the use of the
> >> getStructFieldData method on the inspector. Looking at the definition
> of the
> >> method:
> >>
> >> public Object getStructFieldData(Object data, StructField fieldRef);
> >>
> >> I understand that the use of this method is to retrieve the specific
> given
> >> field from the buffer. However, what I don't understand is what is it
> >> expected to return. I looked around the tests and related code and
> mostly
> >> stuff returned was either a LazyPrimitive or a LazyNonPrimitive, but I
> >> couldn't find anything that enforces this(specially given that the
> return
> >> type is a plain "Object")! Does this mean that I am free to return even
> my
> >> custom object as a return type of this method? If so, what is the
> guarantee
> >> that it will be interpreted correctly down the pipeline?
> >>
> >> Thanks,
> >> --
> >> Swarnim
> >
> >
> >
> >
> > --
> > Swarnim
>

--
Swarnim