You are viewing a plain text version of this content. The canonical link for it is here.
Posted to common-user@hadoop.apache.org by dealmaker <vi...@gmail.com> on 2009/06/03 23:41:33 UTC
Do I need to implement Readfields and Write Functions If I have
Only One Field?
Hi,
I have only one field for the record. I wonder if I even need to define a
member variable in class Record. Do I even need to implement readfields and
write functions if I have only one field? Can I just use the "value" object
directly instead of a member variable of value object?
Thanks.
--
View this message in context: http://www.nabble.com/Do-I-need-to-implement-Readfields-and-Write-Functions-If-I-have-Only-One-Field--tp23860009p23860009.html
Sent from the Hadoop core-user mailing list archive at Nabble.com.
Re: Do I need to implement Readfields and Write Functions If I have
Only One Field?
Posted by Aaron Kimball <aa...@cloudera.com>.
If you don't add any member fields, then no, I don't think you need to
change anything.
- Aaron
On Wed, Jun 3, 2009 at 4:11 PM, dealmaker <vi...@gmail.com> wrote:
>
> I have the following as my type of my "value" object. Do I need to
> implement
> readfields and write functions?
>
> private static class StringArrayWritable extends ArrayWritable {
> private StringArrayWritable (String [] aSString) {
> super (aSString);
> }
> }
>
>
> Aaron Kimball-3 wrote:
> >
> > If you can use an existing serializeable type to hold that field (e.g.,
> if
> > it's an integer, then use IntWritable) then you can just get away with
> > that.
> > If you are specifying your own class for a key or value class, then yes,
> > the
> > class must implement readFields() and write().
> >
> > There's no concept of introspection or other "magic" to determine how to
> > serialize types by decomposing them into more primitive types - you must
> > manually insert the logic for this in every class you use.
> >
> > - Aaron
> >
> > On Wed, Jun 3, 2009 at 2:41 PM, dealmaker <vi...@gmail.com> wrote:
> >
> >>
> >> Hi,
> >> I have only one field for the record. I wonder if I even need to
> define
> >> a
> >> member variable in class Record. Do I even need to implement readfields
> >> and
> >> write functions if I have only one field? Can I just use the "value"
> >> object
> >> directly instead of a member variable of value object?
> >> Thanks.
> >> --
> >> View this message in context:
> >>
> http://www.nabble.com/Do-I-need-to-implement-Readfields-and-Write-Functions-If-I-have-Only-One-Field--tp23860009p23860009.html
> >> Sent from the Hadoop core-user mailing list archive at Nabble.com.
> >>
> >>
> >
> >
>
> --
> View this message in context:
> http://www.nabble.com/Do-I-need-to-implement-Readfields-and-Write-Functions-If-I-have-Only-One-Field--tp23860009p23861181.html
> Sent from the Hadoop core-user mailing list archive at Nabble.com.
>
>
Re: Do I need to implement Readfields and Write Functions If I have
Only One Field?
Posted by dealmaker <vi...@gmail.com>.
I have the following as my type of my "value" object. Do I need to implement
readfields and write functions?
private static class StringArrayWritable extends ArrayWritable {
private StringArrayWritable (String [] aSString) {
super (aSString);
}
}
Aaron Kimball-3 wrote:
>
> If you can use an existing serializeable type to hold that field (e.g., if
> it's an integer, then use IntWritable) then you can just get away with
> that.
> If you are specifying your own class for a key or value class, then yes,
> the
> class must implement readFields() and write().
>
> There's no concept of introspection or other "magic" to determine how to
> serialize types by decomposing them into more primitive types - you must
> manually insert the logic for this in every class you use.
>
> - Aaron
>
> On Wed, Jun 3, 2009 at 2:41 PM, dealmaker <vi...@gmail.com> wrote:
>
>>
>> Hi,
>> I have only one field for the record. I wonder if I even need to define
>> a
>> member variable in class Record. Do I even need to implement readfields
>> and
>> write functions if I have only one field? Can I just use the "value"
>> object
>> directly instead of a member variable of value object?
>> Thanks.
>> --
>> View this message in context:
>> http://www.nabble.com/Do-I-need-to-implement-Readfields-and-Write-Functions-If-I-have-Only-One-Field--tp23860009p23860009.html
>> Sent from the Hadoop core-user mailing list archive at Nabble.com.
>>
>>
>
>
--
View this message in context: http://www.nabble.com/Do-I-need-to-implement-Readfields-and-Write-Functions-If-I-have-Only-One-Field--tp23860009p23861181.html
Sent from the Hadoop core-user mailing list archive at Nabble.com.
Re: Do I need to implement Readfields and Write Functions If I have
Only One Field?
Posted by Aaron Kimball <aa...@cloudera.com>.
If you can use an existing serializeable type to hold that field (e.g., if
it's an integer, then use IntWritable) then you can just get away with that.
If you are specifying your own class for a key or value class, then yes, the
class must implement readFields() and write().
There's no concept of introspection or other "magic" to determine how to
serialize types by decomposing them into more primitive types - you must
manually insert the logic for this in every class you use.
- Aaron
On Wed, Jun 3, 2009 at 2:41 PM, dealmaker <vi...@gmail.com> wrote:
>
> Hi,
> I have only one field for the record. I wonder if I even need to define a
> member variable in class Record. Do I even need to implement readfields
> and
> write functions if I have only one field? Can I just use the "value"
> object
> directly instead of a member variable of value object?
> Thanks.
> --
> View this message in context:
> http://www.nabble.com/Do-I-need-to-implement-Readfields-and-Write-Functions-If-I-have-Only-One-Field--tp23860009p23860009.html
> Sent from the Hadoop core-user mailing list archive at Nabble.com.
>
>