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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Trivial Update of "Hbase/DesignOverview" by EvgenyRyabitskiy
Date Thu, 05 Mar 2009 23:44:45 GMT
Dear Wiki user,

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

------------------------------------------------------------------------------
  [[Anchor(datamodel)]]
  = Data Model =
  
- HBase uses a data model very similar to that of Bigtable. Applications store data rows in
labeled tables. A data row has a sortable row key and an arbitrary number of columns. The
table is stored sparsely, so that rows in the same table can have widely varying numbers of
columns. 
+ Applications store data rows in labeled tables. A data row has a sortable row key and an
arbitrary number of columns. The table is stored sparsely, so that rows in the same table
can have widely varying numbers of columns. 
  
  A column name has the form ''"<family>:<label>"'' where <family> and <label>
can be arbitrary byte arrays. A table enforces its set of <family>s (called ''"column
families"''). Adjusting the set of families is done by performing administrative operations
on the table. However, new <label>s can be used in any write operation without pre-announcing
it. HBase stores column families physically close on disk, so the items in a given column
family should have roughly the same read/write characteristics and contain similar data.
  
  Only a single row at a time may be locked by default. Row writes are always atomic, but
it is also possible to lock a single row and perform both read and write operations on that
row atomically.
  
  An extension was added recently to allow multi-row locking, but this is not the default
behavior and must be explicitly enabled.
+ 
+ More details are here [:Hbase/DataModel: The HBase/Bigtable Data Model]
  
  [[Anchor(conceptual)]]
  == Conceptual View ==

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