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Pig >> mail # user >> Unable to load data using PigStorage that was previously stored using PigStorage


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Re: Unable to load data using PigStorage that was previously stored using PigStorage
Hi Jerry,

Like I mentioned in my earlier email "Map values by default are bytearrays.
If you need them to be any other type, you would need to define it
explicitly."

Difference in the 2 statements is one does a cast to "bag" and the other is
a bytearray (default).
On Thu, Apr 18, 2013 at 2:14 PM, Jerry Lam <[EMAIL PROTECTED]> wrote:

> Hi Prashant:
>
> IT WORKS! THANKS!
> What is the difference between :
> "B = foreach A generate (bag{})document#'b' as b;
> and
> B = foreach A generate document#'b' as b:bag{};"
> ?
>
> The latter gives error: java.lang.ClassCastException:
> org.apache.pig.data.DataByteArray cannot be cast to
> org.apache.pig.data.DataBag
>
> Best Regards,
>
> Jerry
>
>
> On Thu, Apr 18, 2013 at 12:34 PM, Prashant Kommireddi
> <[EMAIL PROTECTED]>wrote:
>
> > Well, let me rephrase - the values all have to be the same type if you
> > choose to read all columns in a similar way. If you know in advance its
> > always the value associated with key 'b' that's a bag, why don't you cast
> > that single value?
> >
> > B = foreach A generate (bag{})document#'b' as b;
> >
> >
> > On Thu, Apr 18, 2013 at 7:43 AM, Jerry Lam <[EMAIL PROTECTED]> wrote:
> >
> > > Hi Prashant:
> > >
> > > I read about the map data type in the book "Programming Pig", it says:
> > > "... By default there is no requirement that all values in a map must
> be
> > of
> > > the same type. It is legitimate to have a map with two keys name and
> age,
> > > where the value for name is a chararray and the value for age is an
> int.
> > > Beginning in Pig 0.9, a map can declare its values to all be of the
> same
> > > type... "
> > >
> > > I agree that all values in the map can be of the same type but this is
> > not
> > > required in pig.
> > >
> > > Best Regards,
> > >
> > > Jerry
> > >
> > >
> > > On Thu, Apr 18, 2013 at 10:37 AM, Jerry Lam <[EMAIL PROTECTED]>
> > wrote:
> > >
> > > > Hi Rusian:
> > > >
> > > > I used PigStorage to store the data that is originally using Pig data
> > > > type. It is strange (or a bug in Pig) that I cannot read the data
> using
> > > > PigStorage that have been stored using PigStorage, isn't it?
> > > >
> > > > Best Regards,
> > > >
> > > > Jerry
> > > >
> > > >
> > > >
> > > > On Wed, Apr 17, 2013 at 10:52 PM, Ruslan Al-Fakikh <
> > [EMAIL PROTECTED]
> > > >wrote:
> > > >
> > > >> The output:
> > > >> ({ ([c#11,d#22]),([c#33,d#44]) })
> > > >> ()
> > > >> looks weird.
> > > >>
> > > >> Jerry, maybe the problem is in using PigStorage. As its javadoc
> says:
> > > >>
> > > >> A load function that parses a line of input into fields using a
> > > character
> > > >> delimiter
> > > >>
> > > >> So I guess this is just for simple csv lines.
> > > >> But you are trying to load a complicated Map structure as it was
> > > formatted
> > > >> by previous storing.
> > > >> Probably you'll need to write your own Loader for this. Another
> hint:
> > > >> using
> > > >> the -schema paramenter to PigStorage, but I am not sure it can
> help:(
> > > >>
> > > >> Ruslan
> > > >>
> > > >>
> > > >> On Wed, Apr 17, 2013 at 11:48 PM, Jerry Lam <[EMAIL PROTECTED]>
> > > wrote:
> > > >>
> > > >> > Hi Rusian:
> > > >> >
> > > >> > I did a describe B followed by a dump B, the output is:
> > > >> > B: {b: {()}}
> > > >> >
> > > >> > ({ ([c#11,d#22]),([c#33,d#44]) })
> > > >> > ()
> > > >> >
> > > >> > but when I executed
> > > >> >
> > > >> > C = foreach B generate flatten(b);
> > > >> >
> > > >> > dump C;
> > > >> >
> > > >> > I got the exception again...
> > > >> >
> > > >> > 2013-04-17 15:47:39,933 [Thread-26] WARN
> > > >> >  org.apache.hadoop.mapred.LocalJobRunner - job_local_0002
> > > >> > java.lang.Exception: java.lang.ClassCastException:
> > > >> > org.apache.pig.data.DataByteArray cannot be cast to
> > > >> > org.apache.pig.data.DataBag
> > > >> > at
> > > >>
> > org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:400)
> > > >> > Caused by: java.lang.ClassCastException:
> > > >> org.apache.pig.data.DataByteArray