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Posted to issues@hbase.apache.org by "jiraposter@reviews.apache.org (Commented) (JIRA)" <ji...@apache.org> on 2012/02/01 03:30:57 UTC
[jira] [Commented] (HBASE-4608) HLog Compression
[ https://issues.apache.org/jira/browse/HBASE-4608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13197521#comment-13197521 ]
jiraposter@reviews.apache.org commented on HBASE-4608:
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https://reviews.apache.org/r/2740/#review4732
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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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