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Posted to common-commits@hadoop.apache.org by Apache Wiki <wi...@apache.org> on 2009/02/07 09:39:46 UTC

[Hadoop Wiki] Update of "Hbase/NewFileFormat" by NitayJoffe

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

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  !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.