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https://issues.apache.org/jira/browse/HBASE-4608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13228954#comment-13228954
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Zhihong Yu commented on HBASE-4608:
-----------------------------------
Please wrap long line:
{code}
+ public static final String ENABLE_WAL_COMPRESSION =
"hbase.regionserver.wal.enablecompression";
{code}
w.r.t. the following code:
{code}
+ static final int VERSION = COMPRESSION_VERSION;
+ static final Text WAL_VERSION = new Text("" + VERSION);
{code}
It implies that WAL_VERSION is the same as COMPRESSION_VERSION.
As I explained earlier, we would likely have another compression scheme for WAL
in the future, resulting in the introduction of PREFIX_COMPRESSION_VERSION e.g.
Then we face a choice: what value would WAL_VERSION carry ?
I propose naming COMPRESSION_VERSION above DICTIONARY_COMPRESSION_VERSION and
decouple it from WAL_VERSION.
In the future, WAL_VERSION of 2 can carry either dictionary or prefix
compression.
> 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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