Hi Stack and Erik,
Thanks for your answers. I think the timestamp is also contain in mapfiles
(in binary format?),
am I right?
Hfile looks better. I will migrate my prog. to hadoop 0.20 and hbase 0.20
after I finished my experiments in 0.19.
But it needs some efforts for those imcompatible apis... :P
stchu
2009/9/23 stack <st...@duboce.net>
> Yes, what Erik said. MapFile is a binary format. What you are some
> preamble up front listing the key and value class types plus some
> miscellaneous meta data. Then, per key and value, these are serialized
> Writable types.
>
> Move to hbase 0.20.0. It uses hfile instead of mapfile. There is a nice
> little utility that does a toString on the hfile binary serializations that
> prints prettier than the below.
>
> St.Ack
>
>
> On Tue, Sep 22, 2009 at 3:10 AM, stchu <stchu.cl...@gmail.com> wrote:
>
> > Hi,
> >
> > I use Hadoop 0.19.1 and HBase 0.19.3.
> > I write a simple table which have 2 column families (Level0:trail_id,
> > Level1:trail_id).
> > And I put the data (4 rows) into hbase table:
> > 120_25 column=Level0:trail_id,
> > timestamp=2009091613240001, value=39999;21234
> > 121.1_23.4 column=Level1:trail_id,
> > timestamp=2009091613240001, value=50001;00048;111110
> > 121.1_25.0 column=Level1:trail_id,
> > timestamp=2009091613240001, value=39999;21234
> > 121_25 column=Level0:trail_id,
> > timestamp=2009091613240003, value=39999;21234;000001;000003
> >
> >
> > I find the content of files in HDFS is:
> >
> > for the mapfile Level0:
> > SEQ
> >
> !org.apache.hadoop.hbase.HStoreKey1org.apache.hadoop.hbase.io.ImmutableBytesWritable�������h
> > =
> > �p{9
> > ��1������.��� 120_25 Level0:trail_id� #B ����� 39999;21234���<���
> 121_25
> > Level0:trail_id� #B ����� 39999;21234;000001;000003
> >
> > for the mapfile Level1:
> > SEQ
> >
> !org.apache.hadoop.hbase.HStoreKey1org.apache.hadoop.hbase.io.ImmutableBytesWritable�������>T�
> > �4�q-�� ��.���9���#
> > 121.1_23.4 Level1:trail_id� #B ����� 50001;00048;111110���2���#
> > 121.1_25.0 Level1:trail_id� #B ����� 39999;21234
> >
> >
> > I wonder that what the messy code means? Is that "offset" and/or
> > "timestamps"?
> > Besides, since hbase store the mapfile depends on columnfamily, why we
> need
> > to save that (in this case: Level0 and Level1)?
> >
> > I appreciate your helps or guides.
> >
> > stchu
> >
>
