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https://issues.apache.org/jira/browse/HBASE-4608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13226764#comment-13226764
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Zhihong Yu commented on HBASE-4608:
-----------------------------------
I cannot go to bed if the answer is still No :-)
With patch v22, I was able to perform decompression/compression round-trip.
See the timestamp of the files below:
{code}
-rwxrwxrwx 1 zhihyu 110088321 99406052 Mar 9 21:38 sea-lab-3.comp
-rwxrwxrwx 1 zhihyu 110088321 100664533 Mar 9 21:36 sea-lab-3.decomp
-rw-r--r-- 1 zhihyu 110088321 99406052 Mar 9 21:18
sea-lab-3%2C60020%2C1331337114819.1331337244655
{code}
The fix is the second line below:
{code}
while ((e = in.next()) != null) {
if (compress) e.enableCompression(null);
{code}
This is because Entry e would be carrying non-null context after the in.next()
call if the input was compressed HLog.
This context needs to be stripped before we pass the Entry to writer.
Patch v22 should be close to the state of checkin.
> 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
> Fix For: 0.94.0
>
> Attachments: 4608-v19.txt, 4608-v20.txt, 4608v1.txt, 4608v13.txt,
> 4608v13.txt, 4608v14.txt, 4608v15.txt, 4608v16.txt, 4608v17.txt, 4608v18.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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