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https://issues.apache.org/jira/browse/HBASE-4608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13228957#comment-13228957
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stack commented on HBASE-4608:
------------------------------
bq. I noticed the size of sv4r25s8%3A60020.1331661889339.decompressed is
different from that of sv4r25s8%3A60020.1331661889339
Because it has metadata the original doesn't have. When I compress it, it
compresses down to same size. Notice that the decompressed and
decompressed.again are same size because they both have the new meata data.
bq. The sentence involving COMPRESSION_VERSION was in past tense but I don't
see it in patch v23.
Pardon me. Should have uploaded v24.
Testing has turned up a minor issue... will upload v25 soon.
bq. In my opinion, this version corresponds to the major version in my comment
@ 13/Mar/12 01:37
Nope. This is the global version that introduces compression. No need of
major/minor granularity, and in particular major/minor on the compression
feature itself. Its overkill.
bq. I agree that both version and compression type should be checked. However,
the order should be checking compression type followed by checking version.
Nope. First figure if we have a file that does compression. Then figure what
type of compression the file does.
> 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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