hadoop-common-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Apache Wiki <wikidi...@apache.org>
Subject [Lucene-hadoop Wiki] Update of "SequenceFile" by Arun C Murthy
Date Thu, 17 Aug 2006 04:56:24 GMT
Dear Wiki user,

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

The following page has been changed by Arun C Murthy:
http://wiki.apache.org/lucene-hadoop/SequenceFile

------------------------------------------------------------------------------
  There are 3 different !SequenceFile formats:
   1. Uncompressed key/value records.
   2. Record compressed key/value records - only 'values' are compressed here.
-  3. Block compressed key/value records - both keys are values are collected in 'blocks'
separately and compressed.
+  3. Block compressed key/value records - both keys are values are collected in 'blocks'
separately and compressed.The size of the 'block' is configurable.
  
  The recommended way is to use the SequenceFile.createWriter methods to construct the 'preferred'
writer implementation.
  
@@ -47, +47 @@

  ===== BlockCompressed Writer Format =====
   * [#SeqFileHeader Header]
   * Record ''Block''
+    * A sync-marker to help in seeking to a random point in the file and then seeking to
next ''record block''.
     * !CompressedKeyLengthsBlockSize
     * !CompressedKeyLengthsBlock
     * !CompressedKeysBlockSize
@@ -55, +56 @@

     * !CompressedValueLengthsBlock
     * !CompressedValuesBlockSize
     * !CompressedValuesBlock
-    * A sync-marker to help in seeking to a random point in the file and then seeking to
next ''record block''.
  

Mime
View raw message