Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Threaded View
Pig, mail # user - Unable to load data using PigStorage that was previously stored using PigStorage


Copy link to this message
-
Re: Unable to load data using PigStorage that was previously stored using PigStorage
Ruslan Al-Fakikh 2013-04-19, 20:56
Hi Jerry,
Sorry I misled you in my suggestions a bit:)
As for your last question: it was interesting for me to investigate the
issue. Here is what I found:
https://issues.apache.org/jira/browse/PIG-2216
https://issues.apache.org/jira/browse/PIG-2315
So here
B = foreach A generate document#'b' as b:bag{};"
due to the misleading Pig syntax/behaviour you are not casting, just
renaming:(

Ruslan

On Fri, Apr 19, 2013 at 2:57 AM, Jerry Lam <[EMAIL PROTECTED]> wrote:

> Hi Prashant:
>
> Just trying to understand my mistake...
> I thought "B = foreach A generate document#'b' as b:bag{};" will cast
> bytearray to bag because of b:bag{}. If I understand correctly, this is not
> what I thought. Am I correct?
>
> Best Regards,
>
> Jerry
>
>
>
>
> On Thu, Apr 18, 2013 at 5:41 PM, Prashant Kommireddi <[EMAIL PROTECTED]
> >wrote:
>
> > 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