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

Switch to Threaded View
Pig, mail # user - wrong sort order (lexical vs numeric) in a nested foreach


Copy link to this message
-
Re: wrong sort order (lexical vs numeric) in a nested foreach
Lauren Blau 2012-09-04, 18:05
unfortunately, I can't put together an example without sharing the custom
jsonloader and data. But I've worked around this by explicitly storing and
reloading the data.
But it sounds like you have it backwards in your attempt to be sneaky. The
data actually is an int and should be sorted numerically.
I just read something in another email that leads me to believe I need to
be casting the lhs of values in a foreach..
like foreach x generate (int)field = fieldname: int;

so I'm going to try explicit casts like that.
Thanks,
lauren

On Sat, Sep 1, 2012 at 12:42 AM, Dmitriy Ryaboy <[EMAIL PROTECTED]> wrote:

> I tried to reproduce this and haven't been able to -- all my devious
> attempts to get something that is actually a string to show up as an
> int in "describe" wind up in class cast exceptions and blown up jobs
> (not devious enough, clearly).
>
> Can you give put together an example that reproduces the issue, and
> let us know which version of pig you are running?
>
> Thanks,
> Dmitriy
>
> On Fri, Aug 31, 2012 at 2:42 AM, Lauren Blau
> <[EMAIL PROTECTED]> wrote:
> > Could this be a problem with the original read of the data. It is stored
> in
> > Json format and read with a custom Json loader.
> > If I save the results of the loader to a file using PigStorage and then
> run
> > the same script reading from that file the sort is done numerically.
> >
> > I've had other pig script problems which have been solved by explicitly
> > storing and re-reading using PigStorage.
> > I'm not sure what I can check in the loader (I didn't write it) to see
> what
> > might be causing this,
> > Any hints on how to debug this?
> >
> > Thanks,
> > Lauren
> >
> > On Thu, Aug 30, 2012 at 6:10 PM, Lauren Blau <
> > [EMAIL PROTECTED]> wrote:
> >
> >> sorry, premature email :-).
> >>
> >> relation = key1 ,key2,orderkey1,val; //schema is
> >> (chararray,int,int,chararray);
> >>
> >> groupbykey = group relation by (key1,key2);
> >> foreach groupbykey {
> >>     sorted = order  relation by orderkey1;
> >>     generate flatten($0), MyUDF(sorted);
> >> }
> >>
> >> I notice that when the 'sorted' values arrive in my UDF, they are sorted
> >> lexically, not numerically. I checked the schema on the way in and
> >> orderkey1 is definitely an int.
> >>
> >> Is there any way to force the order by into a numeric sort?
> >>
> >> Thanks,
> >> Lauren
> >>
> >>
> >> On Thu, Aug 30, 2012 at 5:59 PM, Lauren Blau <
> >> [EMAIL PROTECTED]> wrote:
> >>
> >>> I have the following foreach:
> >>>
> >>> foo := foreach bar {
> >>>
> >>>
> >>
>