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https://issues.apache.org/jira/browse/HBASE-4608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13175310#comment-13175310
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jirapos...@reviews.apache.org commented on HBASE-4608:
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Maybe just do this for WALEdits/KeyValues for now and tackle HLogKey later.
Looks like hash collisions in SimpleDictionary could be nasty.

Other than that mostly whitespace.

Cool stuff.


src/main/java/org/apache/hadoop/hbase/regionserver/wal/CompressedKeyValue.java
<https://reviews.apache.org/r/2740/#comment9223>

    Should remove the year line.
    Also some extra whitespace in this file.



src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLogKey.java
<https://reviews.apache.org/r/2740/#comment9237>

    Bunch of whitespace in here.
    As said above, maybe do HLogKey in a separate jira.



src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogReader.java
<https://reviews.apache.org/r/2740/#comment9236>

    bunch of whitespace in here.



src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogReader.java
<https://reviews.apache.org/r/2740/#comment9234>

    whitespace



src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogReader.java
<https://reviews.apache.org/r/2740/#comment9235>

    I know this is not done, yet... But needs to be a fully qualified config 
name.



src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogReader.java
<https://reviews.apache.org/r/2740/#comment9233>

    LOG.debug?



src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogWriter.java
<https://reviews.apache.org/r/2740/#comment9232>

    Hardcoding SimpleDictionary here?



src/main/java/org/apache/hadoop/hbase/regionserver/wal/SimpleDictionary.java
<https://reviews.apache.org/r/2740/#comment9230>

    year...



src/main/java/org/apache/hadoop/hbase/regionserver/wal/SimpleDictionary.java
<https://reviews.apache.org/r/2740/#comment9229>

    What if you have a hash collision?
    You now overwrite the old value that just happens to have the same hash 
code. Is that OK?



src/main/java/org/apache/hadoop/hbase/regionserver/wal/SimpleDictionary.java
<https://reviews.apache.org/r/2740/#comment9231>

    Here too; what happens for hash collisions?



src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALDictionary.java
<https://reviews.apache.org/r/2740/#comment9228>

    Year... And trailing whitespace in here.



src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALEdit.java
<https://reviews.apache.org/r/2740/#comment9225>

    bunch of extra leading whitespace in this file



src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALEdit.java
<https://reviews.apache.org/r/2740/#comment9226>

    Would sure be nice if we had a KeyValue interface and the implementations 
would just do the right thing.



src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALReplay.java
<https://reviews.apache.org/r/2740/#comment9227>

    I assume you'll tests with/without compression.


- Lars


On 2011-12-23 06:00:24, 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 2011-12-23 06:00:24)
bq.  
bq.  
bq.  Review request for hbase, Eli Collins and Todd Lipcon.
bq.  
bq.  
bq.  Summary
bq.  -------
bq.  
bq.  Heres what I have so far. Things are written, and "should work". I need to 
rework the test cases to test this, and put something in the config file to 
enable/disable. Obviously this isn't ready for commit at the moment, but I can 
get those two things done pretty quickly.
bq.  
bq.  Obviously the dictionary is incredibly simple at the moment, I'll come up 
with something cooler sooner. Let me know how this looks.
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/regionserver/wal/CompressedKeyValue.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/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/SimpleDictionary.java 
PRE-CREATION 
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/TestWALReplay.java 
59910bf 
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
>
>
> 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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