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https://issues.apache.org/jira/browse/HBASE-4608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13183023#comment-13183023
 ] 

jirapos...@reviews.apache.org commented on HBASE-4608:
------------------------------------------------------



bq.  On 2012-01-07 05:18:45, Ted Yu wrote:
bq.  > src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java, 
line 35
bq.  > <https://reviews.apache.org/r/2740/diff/8/?file=67060#file67060line35>
bq.  >
bq.  >     Add javadoc please.

Done.


bq.  On 2012-01-07 05:18:45, Ted Yu wrote:
bq.  > src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java, 
line 84
bq.  > <https://reviews.apache.org/r/2740/diff/8/?file=67060#file67060line84>
bq.  >
bq.  >     Please give this config parameter better name.
bq.  >     How about 'hbase.regionserver.wal.compressed' ?

Done.


bq.  On 2012-01-07 05:18:45, Ted Yu wrote:
bq.  > src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java, 
line 91
bq.  > <https://reviews.apache.org/r/2740/diff/8/?file=67060#file67060line91>
bq.  >
bq.  >     Would this be able to hold large number of HLog.Entry's in memory ?

An HLog is at most 400mb, should be okay?


bq.  On 2012-01-07 05:18:45, Ted Yu wrote:
bq.  > src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java, 
line 229
bq.  > <https://reviews.apache.org/r/2740/diff/8/?file=67060#file67060line229>
bq.  >
bq.  >     Since short is signed, how do I know that the return value would be 
positive ?
bq.  >     e.g. (short)0xFE00 == -512

if the hi bit is negative, (we read that), then we do something else, because 
its not part of the dictionary. added an assert anyways.


bq.  On 2012-01-07 05:18:45, Ted Yu wrote:
bq.  > 
src/main/java/org/apache/hadoop/hbase/regionserver/wal/LRUDictionary.java, line 
166
bq.  > <https://reviews.apache.org/r/2740/diff/8/?file=67063#file67063line166>
bq.  >
bq.  >     I suggest naming this class Node.

Done.


bq.  On 2012-01-07 05:18:45, Ted Yu wrote:
bq.  > src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALEdit.java, 
line 74
bq.  > <https://reviews.apache.org/r/2740/diff/8/?file=67067#file67067line74>
bq.  >
bq.  >     Is compressed a better name ?

Done.


bq.  On 2012-01-07 05:18:45, Ted Yu wrote:
bq.  > src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALEdit.java, 
line 127
bq.  > <https://reviews.apache.org/r/2740/diff/8/?file=67067#file67067line127>
bq.  >
bq.  >     White space makes indentation look weird.

fixed.


bq.  On 2012-01-07 05:18:45, Ted Yu wrote:
bq.  > 
src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestLRUDictionary.java, 
line 1
bq.  > <https://reviews.apache.org/r/2740/diff/8/?file=67068#file67068line1>
bq.  >
bq.  >     Please add Apache license.

fixed.


bq.  On 2012-01-07 05:18:45, Ted Yu wrote:
bq.  > 
src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestLRUDictionary.java, 
line 12
bq.  > <https://reviews.apache.org/r/2740/diff/8/?file=67068#file67068line12>
bq.  >
bq.  >     Add short javadoc and test category, please.

test category - small?


bq.  On 2012-01-07 05:18:45, Ted Yu wrote:
bq.  > 
src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALReplayCompressed.java,
 line 2
bq.  > <https://reviews.apache.org/r/2740/diff/8/?file=67070#file67070line2>
bq.  >
bq.  >     Please remove year.

Done.


bq.  On 2012-01-07 05:18:45, Ted Yu wrote:
bq.  > 
src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALReplayCompressed.java,
 line 29
bq.  > <https://reviews.apache.org/r/2740/diff/8/?file=67070#file67070line29>
bq.  >
bq.  >     You will add the real test, right ?
bq.  >     
bq.  >     Also, missing test category.

This is actually a really good test. If testWALReplay works after compression 
is enabled, then the compression/decompression is working. This is the real 
test.


- Li


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On 2012-01-10 02:34:06, 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 2012-01-10 02:34:06)
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 5120a3c 
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 24407af 
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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