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https://issues.apache.org/jira/browse/HBASE-4608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13228979#comment-13228979
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stack commented on HBASE-4608:
------------------------------
I took a random set of 40 logs off our front end and did a cycle of compress,
decompress multiple times in a row and verified the compressed version always
ends up the same size. No errors.
I'm seeing a pretty consistent 44% of original size compression:
{code}
pynchon:sv4r21s12,60020,1331025586905 stack$ echo "10561645/23441144"|bc -l
.45056013477840501299
pynchon:sv4r21s12,60020,1331025586905 stack$ echo "28127053/63755003"|bc -l
.44117405186225150048
pynchon:sv4r21s12,60020,1331025586905 stack$ echo "28309792/63756667"|bc -l
.44402873192853697951
pynchon:sv4r21s12,60020,1331025586905 stack$ echo "28318314/63754114"|bc -l
.44418018263103773977
...
{code}
> 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, 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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