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https://issues.apache.org/jira/browse/HBASE-4608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13197591#comment-13197591
 ] 

[email protected] commented on HBASE-4608:
------------------------------------------------------



bq.  On 2012-02-01 02:50:08, Ted Yu wrote:
bq.  > src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java, 
line 100
bq.  > <https://reviews.apache.org/r/2740/diff/16/?file=70702#file70702line100>
bq.  >
bq.  >     If we use 
http://docs.oracle.com/javase/6/docs/api/java/util/concurrent/ArrayBlockingQueue.html#offer%28E,%20long,%20java.util.concurrent.TimeUnit%29,
 we should be able to tell that the queue is full.
bq.  >     This implies that readFile() would be called multiple times for a 
single file.

That's beside the point. Using a queue here is just silly. reading a file 
should probably be a different interface altogether rather than writing to a 
queue -- ie it should be a pull interface, not a push.

I also mentioned to Li offline that it would make sense to add a metadata 
header to the HLog sequencefiles which indicates that they're compressed. In 
that case, this code could just use the existing log reader code and log writer 
code, but vary the output between compressed/uncompressed using the 
configuration flag.


- Todd


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On 2012-01-24 22:29:18, Li Pi wrote:
bq.  
bq.  -----------------------------------------------------------
bq.  This is an automatically generated e-mail. To reply, visit:
bq.  https://reviews.apache.org/r/2740/
bq.  -----------------------------------------------------------
bq.  
bq.  (Updated 2012-01-24 22:29:18)
bq.  
bq.  
bq.  Review request for hbase, Eli Collins and Todd Lipcon.
bq.  
bq.  
bq.  Summary
bq.  -------
bq.  
bq.  HLog compression. Has unit tests and a command line tool for 
compressing/decompressing.
bq.  
bq.  
bq.  This addresses bug HBase-4608.
bq.      https://issues.apache.org/jira/browse/HBase-4608
bq.  
bq.  
bq.  Diffs
bq.  -----
bq.  
bq.    src/main/java/org/apache/hadoop/hbase/HConstants.java 8370ef8 
bq.    
src/main/java/org/apache/hadoop/hbase/regionserver/wal/CompressedKeyValue.java 
PRE-CREATION 
bq.    
src/main/java/org/apache/hadoop/hbase/regionserver/wal/CompressionContext.java 
PRE-CREATION 
bq.    src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java 
PRE-CREATION 
bq.    src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLog.java e46a7a0 
bq.    src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLogKey.java 
f067221 
bq.    
src/main/java/org/apache/hadoop/hbase/regionserver/wal/LRUDictionary.java 
PRE-CREATION 
bq.    
src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogReader.java
 d9cd6de 
bq.    
src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogWriter.java
 cbef70f 
bq.    
src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALDictionary.java 
PRE-CREATION 
bq.    src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALEdit.java 
e1117ef 
bq.    
src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestLRUDictionary.java 
PRE-CREATION 
bq.    
src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALReplay.java 
59910bf 
bq.    
src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALReplayCompressed.java
 PRE-CREATION 
bq.  
bq.  Diff: https://reviews.apache.org/r/2740/diff
bq.  
bq.  
bq.  Testing
bq.  -------
bq.  
bq.  
bq.  Thanks,
bq.  
bq.  Li
bq.  
bq.


                
> HLog Compression
> ----------------
>
>                 Key: HBASE-4608
>                 URL: https://issues.apache.org/jira/browse/HBASE-4608
>             Project: HBase
>          Issue Type: New Feature
>            Reporter: Li Pi
>            Assignee: Li Pi
>         Attachments: 4608v1.txt, 4608v5.txt, 4608v6.txt, 4608v7.txt, 
> 4608v8fixed.txt
>
>
> The current bottleneck to HBase write speed is replicating the WAL appends 
> across different datanodes. We can speed up this process by compressing the 
> HLog. Current plan involves using a dictionary to compress table name, region 
> id, cf name, and possibly other bits of repeated data. Also, HLog format may 
> be changed in other ways to produce a smaller HLog.

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