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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Trivial Update of "Hbase/DesignOverview" by EvgenyRyabitskiy
Date Thu, 02 Apr 2009 22:07:05 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for change notification.

The following page has been changed by EvgenyRyabitskiy:
http://wiki.apache.org/hadoop/Hbase/DesignOverview

------------------------------------------------------------------------------
    * [#conceptual Conceptual View]
    * [#physical Physical Storage View]
     * [#regions Regions(Rowranges)]
+  * [#api API]
   * [#design Architecture Design]
    * [#master HBaseMaster]
    * [#hregionserv HRegionServer]
    * [#client HBase Client]
- 
+  * [#impl Implementation]
  [[Anchor(intro)]]
  = Introduction =
  
@@ -92, +93 @@

   * !StoreFiles maintain the sparse index in a separate file
   * HBase extends !StoreFiles so that a bloom filter can be employed to enhance negative
lookup performance. The hash function employed is one developed by Bob Jenkins.
  
+ [[Anchor(api)]]
+ = API =
+ 
+ == Client API ==
+ 
+ See the Javadoc for [http://hadoop.apache.org/hbase/docs/current/api/org/apache/hadoop/hbase/client/HTable.html
HTable] and [http://hadoop.apache.org/hbase/docs/current/api/org/apache/hadoop/hbase/client/HBaseAdmin.html
HBaseAdmin]
+ 
+ == Scanner API ==
+ 
+ To obtain a scanner, a Cursor-like row 'iterator' that must be closed, [http://hadoop.apache.org/hbase/docs/current/api/org/apache/hadoop/hbase/client/HTable.html#HTable(org.apache.hadoop.hbase.HBaseConfiguration,%20java.lang.String)
instantiate an HTable], and then invoke ''getScanner''.  This method returns an [http://hadoop.apache.org/hbase/docs/current/api/org/apache/hadoop/hbase/client/Scanner.html
Scanner] against which you call [http://hadoop.apache.org/hbase/docs/current/api/org/apache/hadoop/hbase/client/Scanner.html#next()
next] and ultimately [http://hadoop.apache.org/hbase/docs/current/api/org/apache/hadoop/hbase/client/Scanner.html#close()
close].
+ 
  [[Anchor(design)]]
  = Architecture Design =
  
@@ -212, +224 @@

  
  Should a region be reassigned either by the master for load balancing or because a region
server has died, the client will rescan the META table to determine the new location of the
user region. If the META region has been reassigned, the client will rescan the ROOT region
to determine the new location of the META region. If the ROOT region has been reassigned,
the client will contact the master to determine the new ROOT region location and will locate
the user region by repeating the original process described above.
  
- === Client API ===
+ [[Anchor(impl)]]
+ = Implementation =
+ Here will be details of HBase implementation. 
  
- See the Javadoc for [http://hadoop.apache.org/hbase/docs/current/api/org/apache/hadoop/hbase/client/HTable.html
HTable] and [http://hadoop.apache.org/hbase/docs/current/api/org/apache/hadoop/hbase/client/HBaseAdmin.html
HBaseAdmin]
- 
- 
- ==== Scanner API ====
- 
- To obtain a scanner, a Cursor-like row 'iterator' that must be closed, [http://hadoop.apache.org/hbase/docs/current/api/org/apache/hadoop/hbase/client/HTable.html#HTable(org.apache.hadoop.hbase.HBaseConfiguration,%20java.lang.String)
instantiate an HTable], and then invoke ''getScanner''.  This method returns an [http://hadoop.apache.org/hbase/docs/current/api/org/apache/hadoop/hbase/client/Scanner.html
Scanner] against which you call [http://hadoop.apache.org/hbase/docs/current/api/org/apache/hadoop/hbase/client/Scanner.html#next()
next] and ultimately [http://hadoop.apache.org/hbase/docs/current/api/org/apache/hadoop/hbase/client/Scanner.html#close()
close].
- 

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