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https://issues.apache.org/jira/browse/HBASE-4218?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Phabricator updated HBASE-4218:
-------------------------------
Attachment: D447.4.patch
mbautin updated the revision "[jira] [HBASE-4218] Delta encoding for keys in
HFile".
Reviewers: JIRA, tedyu, stack, nspiegelberg, Kannan
Rebased on most recent changes in trunk, fixed conflicts. There are failing
unit tests, and delta compression is not yet aware of the persistent memstore
TS field added in 2856.
REVISION DETAIL
https://reviews.facebook.net/D447
AFFECTED FILES
src/main/java/org/apache/hadoop/hbase/HColumnDescriptor.java
src/main/java/org/apache/hadoop/hbase/KeyValue.java
src/main/java/org/apache/hadoop/hbase/io/HalfStoreFileReader.java
src/main/java/org/apache/hadoop/hbase/io/deltaencoder/BitsetKeyDeltaEncoder.java
src/main/java/org/apache/hadoop/hbase/io/deltaencoder/BufferedDeltaEncoder.java
src/main/java/org/apache/hadoop/hbase/io/deltaencoder/CompressionState.java
src/main/java/org/apache/hadoop/hbase/io/deltaencoder/CopyKeyDeltaEncoder.java
src/main/java/org/apache/hadoop/hbase/io/deltaencoder/DeltaEncodedBlock.java
src/main/java/org/apache/hadoop/hbase/io/deltaencoder/DeltaEncoder.java
src/main/java/org/apache/hadoop/hbase/io/deltaencoder/DeltaEncoderAlgorithms.java
src/main/java/org/apache/hadoop/hbase/io/deltaencoder/DeltaEncoderToSmallBufferException.java
src/main/java/org/apache/hadoop/hbase/io/deltaencoder/DiffKeyDeltaEncoder.java
src/main/java/org/apache/hadoop/hbase/io/deltaencoder/FastDiffDeltaEncoder.java
src/main/java/org/apache/hadoop/hbase/io/deltaencoder/PrefixKeyDeltaEncoder.java
src/main/java/org/apache/hadoop/hbase/io/hfile/AbstractHFileReader.java
src/main/java/org/apache/hadoop/hbase/io/hfile/AbstractHFileWriter.java
src/main/java/org/apache/hadoop/hbase/io/hfile/BlockDeltaEncoder.java
src/main/java/org/apache/hadoop/hbase/io/hfile/BlockType.java
src/main/java/org/apache/hadoop/hbase/io/hfile/EmptyBlockDeltaEncoder.java
src/main/java/org/apache/hadoop/hbase/io/hfile/HFile.java
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlockDeltaEncoder.java
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlockIndex.java
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileReaderV1.java
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileReaderV2.java
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileWriterV1.java
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileWriterV2.java
src/main/java/org/apache/hadoop/hbase/mapreduce/LoadIncrementalHFiles.java
src/main/java/org/apache/hadoop/hbase/regionserver/Store.java
src/main/java/org/apache/hadoop/hbase/regionserver/StoreFile.java
src/main/java/org/apache/hadoop/hbase/regionserver/StoreFileScanner.java
src/main/java/org/apache/hadoop/hbase/regionserver/metrics/SchemaConfigured.java
src/main/ruby/hbase/admin.rb
src/test/java/org/apache/hadoop/hbase/HBaseTestCase.java
src/test/java/org/apache/hadoop/hbase/HFilePerformanceEvaluation.java
src/test/java/org/apache/hadoop/hbase/client/TestFromClientSide.java
src/test/java/org/apache/hadoop/hbase/io/TestHalfStoreFileReader.java
src/test/java/org/apache/hadoop/hbase/io/deltaencoder/RedundantKVGenerator.java
src/test/java/org/apache/hadoop/hbase/io/deltaencoder/TestBufferedDeltaEncoder.java
src/test/java/org/apache/hadoop/hbase/io/deltaencoder/TestDeltaEncoders.java
src/test/java/org/apache/hadoop/hbase/io/hfile/TestCacheOnWrite.java
src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileBlock.java
src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileBlockDeltaEncoder.java
src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileBlockIndex.java
src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileWriterV2.java
src/test/java/org/apache/hadoop/hbase/regionserver/DeltaEncodingSeekPerformance.java
src/test/java/org/apache/hadoop/hbase/regionserver/DeltaEncodingUtil.java
src/test/java/org/apache/hadoop/hbase/regionserver/TestCompactSelection.java
src/test/java/org/apache/hadoop/hbase/regionserver/TestCompaction.java
src/test/java/org/apache/hadoop/hbase/regionserver/TestCompoundBloomFilter.java
src/test/java/org/apache/hadoop/hbase/regionserver/TestFSErrorsExposed.java
src/test/java/org/apache/hadoop/hbase/regionserver/TestStoreFile.java
> 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
> Affects Versions: 0.94.0
> Reporter: Jacek Migdal
> Labels: compression
> Attachments: D447.1.patch, D447.2.patch, D447.3.patch, D447.4.patch,
> open-source.diff
>
>
> 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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