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From "Hudson (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-4218) Data Block Encoding of KeyValues (aka delta encoding / prefix compression)
Date Thu, 26 Jan 2012 03:57:44 GMT

    [ https://issues.apache.org/jira/browse/HBASE-4218?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13193543#comment-13193543
] 

Hudson commented on HBASE-4218:
-------------------------------

Integrated in HBase-TRUNK #2646 (See [https://builds.apache.org/job/HBase-TRUNK/2646/])
    [jira] [HBASE-4218] HFile data block encoding framework and delta encoding
implementation (Jacek Midgal, Mikhail Bautin)

Summary:

Adding a framework that allows to "encode" keys in an HFile data block. We
support two modes of encoding: (1) both on disk and in cache, and (2) in cache
only. This is distinct from compression that is already being done in HBase,
e.g. GZ or LZO. When data block encoding is enabled, we store blocks in cache
in an uncompressed but encoded form. This allows to fit more blocks in cache
and reduce the number of disk reads.

The most common example of data block encoding is delta encoding, where we take
advantage of the fact that HFile keys are sorted and share a lot of common
prefixes, and only store the delta between each pair of consecutive keys.
Initial encoding algorithms implemented are DIFF, FAST_DIFF, and PREFIX.

This is based on the delta encoding patch developed by Jacek Midgal during his
2011 summer internship at Facebook. The original patch is available here:
https://reviews.apache.org/r/2308/diff/.

Test Plan: Unit tests. Distributed load test on a five-node cluster.

Reviewers: JIRA, tedyu, stack, nspiegelberg, Kannan

Reviewed By: Kannan

CC: tedyu, todd, mbautin, stack, Kannan, mcorgan, gqchen

Differential Revision: https://reviews.facebook.net/D447

mbautin : 
Files : 
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/HColumnDescriptor.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/HConstants.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/KeyValue.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/HalfStoreFileReader.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/encoding/BufferedDataBlockEncoder.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/encoding/CompressionState.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/encoding/CopyKeyDataBlockEncoder.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/encoding/DataBlockEncoder.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/encoding/DataBlockEncoding.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/encoding/DiffKeyDeltaEncoder.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/encoding/EncodedDataBlock.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/encoding/EncoderBufferTooSmallException.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/encoding/FastDiffDeltaEncoder.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/encoding/PrefixKeyDeltaEncoder.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/AbstractHFileReader.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/AbstractHFileWriter.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/BlockCacheKey.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/BlockType.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFile.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlockIndex.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileDataBlockEncoder.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileDataBlockEncoderImpl.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFilePrettyPrinter.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileReaderV1.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileReaderV2.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileWriterV1.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileWriterV2.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/LruBlockCache.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/io/hfile/NoOpDataBlockEncoder.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/mapreduce/LoadIncrementalHFiles.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/CompactSplitThread.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/MemStore.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/Store.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/StoreFile.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/StoreFileScanner.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/StoreScanner.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/metrics/SchemaConfigured.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/util/ByteBufferUtils.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/util/CompoundBloomFilter.java
* /hbase/trunk/src/main/ruby/hbase/admin.rb
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/BROKE_TODO_FIX_TestAcidGuarantees.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/HBaseTestCase.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/HBaseTestingUtility.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/HFilePerformanceEvaluation.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/TestAcidGuarantees.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/TestKeyValue.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/client/TestAdmin.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/client/TestFromClientSide.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/TestHalfStoreFileReader.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/TestHeapSize.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/encoding/RedundantKVGenerator.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/encoding/TestBufferedDataBlockEncoder.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/encoding/TestChangingEncoding.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/encoding/TestDataBlockEncoders.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/encoding/TestEncodedSeekers.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/encoding/TestLoadAndSwitchEncodeOnDisk.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/encoding/TestUpgradeFromHFileV1ToEncoding.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/CacheTestUtils.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestCacheOnWrite.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFile.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileBlock.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileBlockIndex.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileDataBlockEncoder.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFilePerformance.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileSeek.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileWriterV2.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/mapreduce/TestImportExport.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/CreateRandomStoreFile.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/DataBlockEncodingTool.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/EncodedSeekPerformanceTest.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/HFileReadWriteTest.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestCompactSelection.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestCompaction.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestCompoundBloomFilter.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestFSErrorsExposed.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestMultiColumnScanner.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestScanWithBloomError.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestSeekOptimizations.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestStoreFile.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestLogRolling.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALReplay.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/util/LoadTestKVGenerator.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/util/LoadTestTool.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/util/MultiThreadedReader.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/util/MultiThreadedWriter.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/util/RestartMetaTest.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/util/TestByteBufferUtils.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/util/TestLoadTestKVGenerator.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/util/TestMiniClusterLoadEncoded.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/util/TestMiniClusterLoadParallel.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/util/TestMiniClusterLoadSequential.java

                
> Data Block Encoding of KeyValues  (aka delta encoding / 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
>            Assignee: Mikhail Bautin
>              Labels: compression
>             Fix For: 0.94.0
>
>         Attachments: 0001-Delta-encoding-fixed-encoded-scanners.patch, 0001-Delta-encoding.patch,
4218-2012-01-14.txt, 4218-v16.txt, 4218.txt, D447.1.patch, D447.10.patch, D447.11.patch, D447.12.patch,
D447.13.patch, D447.14.patch, D447.15.patch, D447.16.patch, D447.17.patch, D447.18.patch,
D447.19.patch, D447.2.patch, D447.20.patch, D447.21.patch, D447.22.patch, D447.23.patch, D447.24.patch,
D447.25.patch, D447.26.patch, D447.3.patch, D447.4.patch, D447.5.patch, D447.6.patch, D447.7.patch,
D447.8.patch, D447.9.patch, Data-block-encoding-2011-12-23.patch, Delta-encoding-2012-01-17_11_09_09.patch,
Delta-encoding-2012-01-25_00_45_29.patch, Delta-encoding-2012-01-25_16_32_14.patch, Delta-encoding.patch-2011-12-22_11_52_07.patch,
Delta-encoding.patch-2012-01-05_15_16_43.patch, Delta-encoding.patch-2012-01-05_16_31_44.patch,
Delta-encoding.patch-2012-01-05_16_31_44_copy.patch, Delta-encoding.patch-2012-01-05_18_50_47.patch,
Delta-encoding.patch-2012-01-07_14_12_48.patch, Delta-encoding.patch-2012-01-13_12_20_07.patch,
Delta_encoding_with_memstore_TS.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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