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

Switch to Plain View
Hadoop, mail # general - Hadoop and XML


+
Peter Minearo 2010-07-16, 21:00
+
Soumya Banerjee 2010-07-16, 21:29
+
Peter Minearo 2010-07-16, 21:44
+
Peter Minearo 2010-07-16, 21:51
+
Peter Minearo 2010-07-16, 22:07
+
Ted Yu 2010-07-17, 04:43
+
Peter Minearo 2010-07-19, 15:01
+
Ted Yu 2010-07-19, 16:08
+
Jeff Bean 2010-07-20, 13:01
Copy link to this message
-
Re: Hadoop and XML
Ted Yu 2010-07-20, 15:56
Interesting.
String class is able to handle this scenario:

  348       public String(byte[] data, String encoding) throws
UnsupportedEncodingException {
  349           this(data, 0, data.length, encoding);
  350       }

On Tue, Jul 20, 2010 at 6:01 AM, Jeff Bean <[EMAIL PROTECTED]> wrote:

> I think the problem is here:
>
> String valueString = new String(valueText.getBytes(), "UTF-8");
>
> Javadoc for Text says:
>
> *getBytes<
> http://hadoop.apache.org/common/docs/current/api/org/apache/hadoop/io/Text.html#getBytes%28%29
> >
> *()
>          Returns the raw bytes; however, only data up to
> getLength()<
> http://hadoop.apache.org/common/docs/current/api/org/apache/hadoop/io/Text.html#getLength%28%29
> >is
> valid.
>
> So try getting the length, truncating the byte array at the value returned
> by getLength() and THEN converting it to a String.
>
> Jeff
>
> On Mon, Jul 19, 2010 at 9:08 AM, Ted Yu <[EMAIL PROTECTED]> wrote:
>
> > For your initial question on Text.set().
> > Text.setCapacity() allocates new byte array. Since keepData is false, old
> > data wouldn't be copied over.
> >
> > On Mon, Jul 19, 2010 at 8:01 AM, Peter Minearo <
> > [EMAIL PROTECTED]> wrote:
> >
> > > I am already using XmlInputFormat.  The input into the Map phase is not
> > > the problem.  The problem lays in between the Map and Reduce phase.
> > >
> > > BTW - The article is correct.  DO NOT USE StreamXmlRecordReader.
> > > XmlInputFormat is a lot faster.  From my testing, StreamXmlRecordReader
> > > took 8 minutes to read a 1 GB XML document; where as, XmlInputFormat
> was
> > > under 2 minutes. (Using 2 Core, 8GB machines)
> > >
> > >
> > > -----Original Message-----
> > > From: Ted Yu [mailto:[EMAIL PROTECTED]]
> > > Sent: Friday, July 16, 2010 9:44 PM
> > > To: [EMAIL PROTECTED]
> > > Subject: Re: Hadoop and XML
> > >
> > > From an earlier post:
> > > http://oobaloo.co.uk/articles/2010/1/20/processing-xml-in-hadoop.html
> > >
> > > On Fri, Jul 16, 2010 at 3:07 PM, Peter Minearo <
> > > [EMAIL PROTECTED]> wrote:
> > >
> > > > Moving the variable to a local variable did not seem to work:
> > > >
> > > >
> > > > </PrivateRateSet>vateRateSet>
> > > >
> > > >
> > > >
> > > > public void map(Object key, Object value, OutputCollector output,
> > > > Reporter
> > > > reporter) throws IOException {
> > > >                Text valueText = (Text)value;
> > > >                String valueString = new String(valueText.getBytes(),
> > > > "UTF-8");
> > > >                String keyString = getXmlKey(valueString);
> > > >                 Text returnKeyText = new Text();
> > > >                Text returnValueText = new Text();
> > > >                returnKeyText.set(keyString);
> > > >                returnValueText.set(valueString);
> > > >                output.collect(returnKeyText, returnValueText); }
> > > >
> > > > -----Original Message-----
> > > > From: Peter Minearo [mailto:[EMAIL PROTECTED]]
> > > > Sent: Fri 7/16/2010 2:51 PM
> > > > To: [EMAIL PROTECTED]
> > > > Subject: RE: Hadoop and XML
> > > >
> > > > Whoops....right after I sent it and someone else made a suggestion; I
> > > > realized what question 2 was about.  I can try that, but wouldn't
> that
> > >
> > > > cause Object bloat?  During the Hadoop training I went through; it
> was
> > >
> > > > mentioned to reuse the returning Key and Value objects to keep the
> > > > number of Objects created down to a minimum.  Is this not really a
> > > > valid point?
> > > >
> > > >
> > > >
> > > > -----Original Message-----
> > > > From: Peter Minearo [mailto:[EMAIL PROTECTED]]
> > > > Sent: Friday, July 16, 2010 2:44 PM
> > > > To: [EMAIL PROTECTED]
> > > > Subject: RE: Hadoop and XML
> > > >
> > > >
> > > > I am not using multi-threaded Map tasks.  Also, if I understand your
> > > > second question correctly:
> > > > "Also can you try creating the output key and values in the map
> > > > method(method lacal) ?"
+
Jeff Bean 2010-07-20, 16:23
+
Ted Yu 2010-07-20, 16:38
+
Ted Yu 2010-07-20, 16:50
+
Peter Minearo 2010-07-20, 16:35
+
Scott Carey 2010-07-20, 18:24
+
Scott Carey 2010-07-20, 18:29