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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "Hbase/NewFileFormat" by NitayJoffe
Date Sat, 07 Feb 2009 08:39:46 GMT
Dear Wiki user,

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

------------------------------------------------------------------------------
  
  !MapFiles can be configured to compress each key/value entry or compress based off a block
size.  Blocks do not span key/values but break on entries.
  
- Hbase keys are made of key/column/timestamp.  Rows and columns are effectively binary. 
Timestamp is a long.  The sort is not a straight-forward binary sort; it has its idiosyncrasies
embodied in the particular Comparator passed creating the store file: e.g. The timestamps
are in reverse order because we want to find the newest first.
+ Hbase keys are made of row/column/timestamp.  Rows and columns are effectively binary. 
Timestamp is a long.  The sort is not a straight-forward binary sort; it has its idiosyncrasies
embodied in the particular Comparator passed creating the store file: e.g. The timestamps
are in reverse order because we want to find the newest first.
  
  Every hbase flush creates a new !MapFile in the file system and an accompanying SequenceFile
of metadata, an 'info' file.  Metadata includes the id of the last edit added the !MapFile
and if the store file is a 'reference' file -- more on this later (TODO) -- it also includes
info on whats referred to.
  

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