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From stack <st...@duboce.net>
Subject Re: Reading table sequentially...
Date Wed, 13 Jan 2010 00:46:52 GMT
On Tue, Jan 12, 2010 at 2:01 PM, Something Something <
mailinglists19@gmail.com> wrote:

> All the Keys returned by this code are guaranteed to be in order by the key
> values, correct?
>

No.  Explicitly, the order is NOT guaranteed, for performance reasons (I
don't see this in the javadoc.  It should be there).  If just getting latest
version from a set of columns, I believe it will come across in the right
order but not guaranteed.  To get a guaranteed sorted order, call
http://hadoop.apache.org/hbase/docs/current/api/org/apache/hadoop/hbase/client/Result.html#sorted()instead
of the raw() method.  The sort will be done client-side.


>
> Also, for some other table I am retrieving all column names for a
> particular
> key, and those all seem to be in the correct order as well.  Is this always
> guaranteed?
>

 Call sort if you need guarantee.

St.Ack







>
> On Tue, Jan 12, 2010 at 11:12 AM, stack <stack@duboce.net> wrote:
>
> > Setup the scanner and next it as you did previous.  Then on the Result
> > object, do something like:
> >
> > for (KeyValue kv: result.raw()) {
> >  System.out.println(Bytes.toString(kv.getRow()) + " " +
> > Bytes.toString(kv.getValue()));
> > }
> >
> > St.Ack
> >
> > On Tue, Jan 12, 2010 at 10:24 AM, Something Something <
> > mailinglists19@gmail.com> wrote:
> >
> > > Sorry.  That was a typo.  In any case, it seems like I am using the
> wrong
> > > API.
> > >
> > > Here's what my table contains:
> > >
> > >
> > >  ABC_111                     column=info:estimate,
> > timestamp=1263319888463,
> > > value=179.59
> > >  ABC_222                     column=info:estimate,
> > timestamp=1263319888463,
> > > value=191.50
> > >  ABC_333                     column=info:estimate,
> > timestamp=1263319888463,
> > > value=180.65
> > >  ABC_444                     column=info:estimate,
> > timestamp=1263319888463,
> > > value=183.63
> > >  & so on....
> > >
> > >
> > > I want to retrieve:
> > >
> > > ABC_111  179.59
> > > ABC_222  191.50
> > > ABC_333  180.65
> > > ABC_444  183.63
> > > & so on...
> > >
> > > What API should I use?  Please let me know.  Thanks for your help.
> > >
> > >
> > > On Tue, Jan 12, 2010 at 9:36 AM, stack <stack@duboce.net> wrote:
> > >
> > > > See below:
> > > >
> > > > On Tue, Jan 12, 2010 at 9:12 AM, Something Something <
> > > > mailinglists19@gmail.com> wrote:
> > > > >
> > > > >            NavigableMap<byte[], NavigableMap<byte[],
> > NavigableMap<Long,
> > > > > byte[]>>> map = result.getMap();
> > > > >
> > > >
> > > > Above returns a map keyed by families:
> > > >
> > > >
> > >
> >
> http://hadoop.apache.org/hbase/docs/current/api/org/apache/hadoop/hbase/client/Result.html#getMap%28%29
> > > >
> > > >
> > > >
> > > >
> > > > >            for (Map.Entry<byte[], NavigableMap<byte[],
> > > NavigableMap<Long,
> > > > > byte[]>>> entry : map.entrySet()) {
> > > > >            byte[] key = entry.getKey();
> > > > >
> > > >
> > > > This is family name, not key.
> > > >
> > > >
> > > >
> > > > >            *LOG.info("key = " + Bytes.toString(key));*
> > > > >            NavigableMap<byte[], NavigableMap<Long, byte[]>>
value =
> > > > > entry.getValue();
> > > > >
> > > >
> > > > This is a map keyed by column qualifiers.
> > > >
> > > >
> > > >
> > > > >              for (Entry<byte[], NavigableMap<Long, byte[]>>
entry1
> :
> > > > > value.entrySet()) {
> > > > >                  byte[] key1 = entry1.getKey();
> > > > >                  *LOG.info("key1 = " + Bytes.toString(key1));*
> > > > >
> > > >
> > > >
> > > > This is the family qualifier.
> > > >
> > > >
> > > >
> > > > >                  NavigableMap<byte[], NavigableMap<Long, byte[]>>
> > > value1
> > > > =
> > > > > entry.getValue();
> > > > >
> > > >
> > > >
> > > > I do not think you intended to do this.  I think you meant entry1,
> not
> > > > 'entry' and map type should be NavigableMap<Long, byte[]> rather
than
> > > > above.
> > > >
> > > > St.Ack
> > > >
> > > >
> > > >
> > > > >                  for (Entry<byte[], NavigableMap<Long, byte[]>>
> > entry2
> > > :
> > > > > value1.entrySet()) {
> > > > >                      String key2 = Bytes.toString(entry2.getKey());
> > > > >                      *LOG.info("key2 = " + key2);*
> > > > >
> > > > >                  }
> > > > >              }
> > > > >            }
> > > > >        }
> > > > >
> > > >
> > >
> >
>

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