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https://issues.apache.org/jira/browse/HBASE-4608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13228946#comment-13228946
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stack commented on HBASE-4608:
------------------------------
Here's my compressing, decompressing, compressing again, decompressing again,
then recompressing a random log file from our front end:
{code}
-rw-r--r-- 1 stack staff 64928728 Mar 13 20:43
sv4r25s8%3A60020.1331661889339
-rwxrwxrwx 1 stack staff 28540761 Mar 13 20:48
sv4r25s8%3A60020.1331661889339.compressed
-rwxrwxrwx 1 stack staff 28540761 Mar 13 20:58
sv4r25s8%3A60020.1331661889339.compressed.again
-rwxrwxrwx 1 stack staff 28540761 Mar 13 21:02
sv4r25s8%3A60020.1331661889339.compressed.again.again
-rwxrwxrwx 1 stack staff 64945799 Mar 13 20:57
sv4r25s8%3A60020.1331661889339.decompressed
-rwxrwxrwx 1 stack staff 64945799 Mar 13 21:02
sv4r25s8%3A60020.1331661889339.decompressed.again
{code}
Its 44% of original size.
> 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, 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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