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https://issues.apache.org/jira/browse/HBASE-4608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13197521#comment-13197521
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[email protected] commented on HBASE-4608:
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Only got about halfway through. Will continue to look soon. Overall looking
pretty good!
src/main/java/org/apache/hadoop/hbase/regionserver/wal/CompressedKeyValue.java
<https://reviews.apache.org/r/2740/#comment10459>
I'd rename this class to KeyValueCompression or even KVCompression. Then
rename readFields to just "read" -- since this is just utility functions, not
actually an instance of a compressed keyvalue.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/CompressedKeyValue.java
<https://reviews.apache.org/r/2740/#comment10460>
rather than using keyVal.getRow(), keyVal.getFamily(),
keyVal.getQualifer(), you should use the versions of those functions that just
return offsets and lengths (eg getKeyOffset, getKeyLength). Then expand the
writeCompressed API to take (byte[] buf, int off, int len). Otherwise you're
making needless copies/garbage here.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/CompressionContext.java
<https://reviews.apache.org/r/2740/#comment10461>
Since this is so simple, I'd move it to be a static inner class of
KVCompression above
src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java
<https://reviews.apache.org/r/2740/#comment10462>
I think we can merge this with the other class that just has static methods
as well.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java
<https://reviews.apache.org/r/2740/#comment10463>
this function requires that the whole log data fit in RAM - not a great
assumption
src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java
<https://reviews.apache.org/r/2740/#comment10464>
why is this split into two if/elses? looks like the top clauses can be
combined, as can the bottom clauses
src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java
<https://reviews.apache.org/r/2740/#comment10465>
switch order of "in" and "offset" here.
Perhaps clearer to name this as "uncompressIntoArray"?
src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java
<https://reviews.apache.org/r/2740/#comment10467>
worth a comment here to explain that the "status" byte actually has the
high-order byte of the dictionary entry in the case that it's in the dictionary
src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java
<https://reviews.apache.org/r/2740/#comment10466>
*un*compressed value, right?
- Todd
On 2012-01-24 22:29:18, Li Pi wrote:
bq.
bq. -----------------------------------------------------------
bq. This is an automatically generated e-mail. To reply, visit:
bq. https://reviews.apache.org/r/2740/
bq. -----------------------------------------------------------
bq.
bq. (Updated 2012-01-24 22:29:18)
bq.
bq.
bq. Review request for hbase, Eli Collins and Todd Lipcon.
bq.
bq.
bq. Summary
bq. -------
bq.
bq. HLog compression. Has unit tests and a command line tool for
compressing/decompressing.
bq.
bq.
bq. This addresses bug HBase-4608.
bq. https://issues.apache.org/jira/browse/HBase-4608
bq.
bq.
bq. Diffs
bq. -----
bq.
bq. src/main/java/org/apache/hadoop/hbase/HConstants.java 8370ef8
bq.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/CompressedKeyValue.java
PRE-CREATION
bq.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/CompressionContext.java
PRE-CREATION
bq. src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java
PRE-CREATION
bq. src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLog.java e46a7a0
bq. src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLogKey.java
f067221
bq.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/LRUDictionary.java
PRE-CREATION
bq.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogReader.java
d9cd6de
bq.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogWriter.java
cbef70f
bq.
src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALDictionary.java
PRE-CREATION
bq. src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALEdit.java
e1117ef
bq.
src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestLRUDictionary.java
PRE-CREATION
bq.
src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALReplay.java
59910bf
bq.
src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALReplayCompressed.java
PRE-CREATION
bq.
bq. Diff: https://reviews.apache.org/r/2740/diff
bq.
bq.
bq. Testing
bq. -------
bq.
bq.
bq. Thanks,
bq.
bq. Li
bq.
bq.
> 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
> Attachments: 4608v1.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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