Problem with using BinSedesTuple as Mapper key

[Gayatri Rao <rg...@gmail.com>]

Hello,

I am using BinSedesTuple as a mapper key to emit a tuple of values. But
somehow same keys do not go to the same reducer and I do not get
aggregates.
Is it not suggested to use it as a mapper key?

For example in my mapper I emit

Mapper:
Output key : BinSedesTuple  value: int


Example output:
tuple.append(url);
tuple.append(category);

Reducer:
Input key: BinSedesTuple value: int
Output key: Text value: int

Example output:
url1 category1 3
url1 category1 2

In the reducer output I get output with multiple keys being the same. My
expected output is
url1 category 5

Any ideas what might be wrong?


Thanks,
Gayatri

Re: Problem with using BinSedesTuple as Mapper key

[Harsh J <ha...@cloudera.com>]

Per http://pig.apache.org/docs/r0.9.1/api/org/apache/pig/data/BinSedesTuple.html
(From where you may have picked up BinSedesTuple), its advised not to
use this class directly, outside of Pig.

You're better off implementing your own writable, or using a better
serialization library that provides similar structures and much more,
such as Apache Avro:
http://avro.apache.org/docs/1.6.3/api/java/org/apache/avro/mapred/package-summary.html#package_description

On Mon, Apr 23, 2012 at 11:00 AM, Gayatri Rao <rg...@gmail.com> wrote:
> Hello,
>
> I am using BinSedesTuple as a mapper key to emit a tuple of values. But
> somehow same keys do not go to the same reducer and I do not get
> aggregates.
> Is it not suggested to use it as a mapper key?
>
> For example in my mapper I emit
>
> Mapper:
> Output key : BinSedesTuple  value: int
>
>
> Example output:
> tuple.append(url);
> tuple.append(category);
>
> Reducer:
> Input key: BinSedesTuple value: int
> Output key: Text value: int
>
> Example output:
> url1 category1 3
> url1 category1 2
>
> In the reducer output I get output with multiple keys being the same. My
> expected output is
> url1 category 5
>
> Any ideas what might be wrong?
>
>
> Thanks,
> Gayatri



-- 
Harsh J

Re: Problem with using BinSedesTuple as Mapper key

[Pere Ferrera <fe...@gmail.com>]

Hi Gayatri,
Looks like you might want to use a low-level enhancement of the default
Hadoop API called Pangool (http://pangool.net) which uses tuples and
simplifies grouping by, sorting by and joining datasets in Hadoop.

On Mon, Apr 23, 2012 at 7:30 AM, Gayatri Rao <rg...@gmail.com> wrote:

> Hello,
>
> I am using BinSedesTuple as a mapper key to emit a tuple of values. But
> somehow same keys do not go to the same reducer and I do not get
> aggregates.
> Is it not suggested to use it as a mapper key?
>
> For example in my mapper I emit
>
> Mapper:
> Output key : BinSedesTuple  value: int
>
>
> Example output:
> tuple.append(url);
> tuple.append(category);
>
> Reducer:
> Input key: BinSedesTuple value: int
> Output key: Text value: int
>
> Example output:
> url1 category1 3
> url1 category1 2
>
> In the reducer output I get output with multiple keys being the same. My
> expected output is
> url1 category 5
>
> Any ideas what might be wrong?
>
>
> Thanks,
> Gayatri
>