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Date: Wed, 14 Mar 2012 04:14:11 +0000 (UTC)
From: "stack (Commented) (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (HBASE-4608) HLog Compression
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    [ https://issues.apache.org/jira/browse/HBASE-4608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13228947#comment-13228947 ] 

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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