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https://issues.apache.org/jira/browse/HBASE-4218?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13123330#comment-13123330
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jirapos...@reviews.apache.org commented on HBASE-4218:
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https://reviews.apache.org/r/2308/
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Review request for hbase.
Summary
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Delta encoding for key values.
This addresses bug HBASE-4218.
https://issues.apache.org/jira/browse/HBASE-4218
Diffs
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/HColumnDescriptor.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/KeyValue.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/HalfStoreFileReader.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/deltaencoder/BitsetKeyDeltaEncoder.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/deltaencoder/BufferedDeltaEncoder.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/deltaencoder/CompressionState.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/deltaencoder/CopyKeyDeltaEncoder.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/deltaencoder/DeltaEncodedBlock.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/deltaencoder/DeltaEncoder.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/deltaencoder/DeltaEncoderAlgorithms.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/deltaencoder/DeltaEncoderToSmallBufferException.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/deltaencoder/DiffKeyDeltaEncoder.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/deltaencoder/FastDiffDeltaEncoder.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/deltaencoder/PrefixKeyDeltaEncoder.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/AbstractHFileReader.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/AbstractHFileWriter.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/BlockDeltaEncoder.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/BlockType.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/EmptyBlockDeltaEncoder.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFile.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlockDeltaEncoder.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlockIndex.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFilePrettyPrinter.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileReaderV1.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileReaderV2.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileWriterV1.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileWriterV2.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/mapreduce/LoadIncrementalHFiles.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/Store.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/StoreFile.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/StoreFileScanner.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/util/CompressionTest.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/ruby/hbase/admin.rb
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http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/HBaseTestCase.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/HFilePerformanceEvaluation.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/TestHalfStoreFileReader.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/deltaencoder/RedundantKVGenerator.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/deltaencoder/TestBufferedDeltaEncoder.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/deltaencoder/TestDeltaEncoders.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/RandomSeek.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestCacheOnWrite.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFile.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileBlock.java
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http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileBlockDeltaEncoder.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileBlockIndex.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFilePerformance.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileReaderV1.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileSeek.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileWriterV2.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestReseekTo.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestSeekTo.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/mapreduce/TestHFileOutputFormat.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/mapreduce/TestLoadIncrementalHFiles.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/DeltaEncodingSeekPerformance.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/DeltaEncodingUtil.java
PRE-CREATION
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestCompactSelection.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestCompaction.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestCompoundBloomFilter.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestFSErrorsExposed.java
1180113
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestStoreFile.java
1180113
Diff: https://reviews.apache.org/r/2308/diff
Testing
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Unit tests, dev cluster, shadow...
Still ongoing.
Thanks,
Jacek
> Delta Encoding of KeyValues (aka prefix compression)
> -----------------------------------------------------
>
> Key: HBASE-4218
> URL: https://issues.apache.org/jira/browse/HBASE-4218
> Project: HBase
> Issue Type: Improvement
> Components: io
> Reporter: Jacek Migdal
> Labels: compression
>
> A compression for keys. Keys are sorted in HFile and they are usually very
> similar. Because of that, it is possible to design better compression than
> general purpose algorithms,
> It is an additional step designed to be used in memory. It aims to save
> memory in cache as well as speeding seeks within HFileBlocks. It should
> improve performance a lot, if key lengths are larger than value lengths. For
> example, it makes a lot of sense to use it when value is a counter.
> Initial tests on real data (key length = ~ 90 bytes , value length = 8 bytes)
> shows that I could achieve decent level of compression:
> key compression ratio: 92%
> total compression ratio: 85%
> LZO on the same data: 85%
> LZO after delta encoding: 91%
> While having much better performance (20-80% faster decompression ratio than
> LZO). Moreover, it should allow far more efficient seeking which should
> improve performance a bit.
> It seems that a simple compression algorithms are good enough. Most of the
> savings are due to prefix compression, int128 encoding, timestamp diffs and
> bitfields to avoid duplication. That way, comparisons of compressed data can
> be much faster than a byte comparator (thanks to prefix compression and
> bitfields).
> In order to implement it in HBase two important changes in design will be
> needed:
> -solidify interface to HFileBlock / HFileReader Scanner to provide seeking
> and iterating; access to uncompressed buffer in HFileBlock will have bad
> performance
> -extend comparators to support comparison assuming that N first bytes are
> equal (or some fields are equal)
> Link to a discussion about something similar:
> http://search-hadoop.com/m/5aqGXJEnaD1/hbase+windows&subj=Re+prefix+compression
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