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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 ==
