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From "jiraposter@reviews.apache.org (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-4608) HLog Compression
Date Wed, 14 Mar 2012 15:14:42 GMT

    [ https://issues.apache.org/jira/browse/HBASE-4608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13229248#comment-13229248
] 

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



bq.  On 2012-03-14 11:46:10, Ted Yu wrote:
bq.  > src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLogKey.java, line 53
bq.  > <https://reviews.apache.org/r/4328/diff/2/?file=92105#file92105line53>
bq.  >
bq.  >     Introducing enum is a good idea.
bq.  >     I would suggest changing this to COMPRESSED_WITH_DICTIONARY or something similar.

HLogKey does not need to know about 'type' of compression.


bq.  On 2012-03-14 11:46:10, Ted Yu wrote:
bq.  > src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLogKey.java, line 306
bq.  > <https://reviews.apache.org/r/4328/diff/2/?file=92105#file92105line306>
bq.  >
bq.  >     How about passing compressionContext and type of field we're reading to Compressor.readCompressed()
?

Generalization is out of scope.


bq.  On 2012-03-14 11:46:10, Ted Yu wrote:
bq.  > src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogReader.java,
line 189
bq.  > <https://reviews.apache.org/r/4328/diff/2/?file=92108#file92108line189>
bq.  >
bq.  >     Hiding LRUDictionary.class is desirable.
bq.  >     Shall we pass this.getMetadata() to CompressionContext ctor where selection
of compression type is made ?

Out of scope.


bq.  On 2012-03-14 11:46:10, Ted Yu wrote:
bq.  > src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogWriter.java,
line 110
bq.  > <https://reviews.apache.org/r/4328/diff/2/?file=92109#file92109line110>
bq.  >
bq.  >     We introduced compression type in Metadata, how about allowing user to specify
compression type using conf ?
bq.  >     Default is dictionary compression.

Customization is out of scope.  "How about..." should have attendant justification.  You can
justify generalization of this compression in a new jira.


bq.  On 2012-03-14 11:46:10, Ted Yu wrote:
bq.  > src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogWriter.java,
line 139
bq.  > <https://reviews.apache.org/r/4328/diff/2/?file=92109#file92109line139>
bq.  >
bq.  >     Hiding LRUDictionary.class is desirable.
bq.  >     How about passing conf to CompressionContext ctor ?

The generalization that would require hiding the type of compression being done is out of
scope.


This is not a software project that fellas are working on for casual amusement.  New facility
should be justified by real-world needs.  This feature is experimental.  It could help w/
our WAL writes.  It may not.  We need to get a basic facility into a release so we can try
it.  If it proves its worth, we can spend more time down this avenue.


- Michael


-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/4328/#review5929
-----------------------------------------------------------


On 2012-03-14 07:34:58, Michael Stack wrote:
bq.  
bq.  -----------------------------------------------------------
bq.  This is an automatically generated e-mail. To reply, visit:
bq.  https://reviews.apache.org/r/4328/
bq.  -----------------------------------------------------------
bq.  
bq.  (Updated 2012-03-14 07:34:58)
bq.  
bq.  
bq.  Review request for hbase.
bq.  
bq.  
bq.  Summary
bq.  -------
bq.  
bq.  See issue
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 045c6f3 
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/Dictionary.java PRE-CREATION

bq.    src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLog.java b5049b1 
bq.    src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLogKey.java 311ea1b 
bq.    src/main/java/org/apache/hadoop/hbase/regionserver/wal/KeyValueCompression.java PRE-CREATION

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 ff63a5f

bq.    src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogWriter.java 01ebb5c

bq.    src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALEdit.java d8f317c 
bq.    src/main/java/org/apache/hadoop/hbase/util/Bytes.java de8e40b 
bq.    src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestCompressor.java PRE-CREATION

bq.    src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestKeyValueCompression.java
PRE-CREATION 
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 a11899c 
bq.    src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALReplayCompressed.java
PRE-CREATION 
bq.  
bq.  Diff: https://reviews.apache.org/r/4328/diff
bq.  
bq.  
bq.  Testing
bq.  -------
bq.  
bq.  
bq.  Thanks,
bq.  
bq.  Michael
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: stack
>             Fix For: 0.94.0
>
>         Attachments: 4608-v19.txt, 4608-v20.txt, 4608-v22.txt, 4608v1.txt, 4608v13.txt,
4608v13.txt, 4608v14.txt, 4608v15.txt, 4608v16.txt, 4608v17.txt, 4608v18.txt, 4608v23.txt,
4608v24.txt, 4608v25.txt, 4608v27.txt, 4608v5.txt, 4608v6.txt, 4608v7.txt, 4608v8fixed.txt,
hbase-4608-v28-delta.txt, hbase-4608-v28.txt, hbase-4608-v28.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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