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Date: Fri, 13 Jan 2012 20:18:47 +0000 (UTC)
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Subject: [jira] [Updated] (HBASE-4218) Data Block Encoding of KeyValues
  (aka delta encoding / prefix compression)
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     [ https://issues.apache.org/jira/browse/HBASE-4218?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Phabricator updated HBASE-4218:
-------------------------------

    Attachment: D447.22.patch

mbautin updated the revision "[jira] [HBASE-4218] HFile data block encoding framework and delta encoding implementation".
Reviewers: JIRA, tedyu, stack, nspiegelberg, Kannan

  Fixing a critical bug in compactions with cache-on-write turned on when encoding is used in cache only. All unit tests pass. I also did the following cluster test:

   * Load LZO-compressed, PREFIX-encoded data, encoding on disk
   * Switch encoding on disk off, load some more data
   * Switch encoding on disk back on, load some more data
   * Run a manual compaction
   * Switch encoding type to FAST_DIFF, turn encoding on disk off, load some more data
   * Switch encoding type to DIFF, turn encoding on disk on, load some more data

  I kept an eye on the logs throughout the above manipulations and made sure that compaction errors I had seen before (with an unencoded scanner trying to read an encoded block) did not show up.

  @Kannan: did you want to take another look at the diff?


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/HConstants.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/encoding/BufferedDataBlockEncoder.java
  src/main/java/org/apache/hadoop/hbase/io/encoding/CompressionState.java
  src/main/java/org/apache/hadoop/hbase/io/encoding/CopyKeyDataBlockEncoder.java
  src/main/java/org/apache/hadoop/hbase/io/encoding/DataBlockEncoder.java
  src/main/java/org/apache/hadoop/hbase/io/encoding/DataBlockEncoding.java
  src/main/java/org/apache/hadoop/hbase/io/encoding/DiffKeyDeltaEncoder.java
  src/main/java/org/apache/hadoop/hbase/io/encoding/EncodedDataBlock.java
  src/main/java/org/apache/hadoop/hbase/io/encoding/EncoderBufferTooSmallException.java
  src/main/java/org/apache/hadoop/hbase/io/encoding/FastDiffDeltaEncoder.java
  src/main/java/org/apache/hadoop/hbase/io/encoding/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/BlockCacheKey.java
  src/main/java/org/apache/hadoop/hbase/io/hfile/BlockType.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/HFileBlockIndex.java
  src/main/java/org/apache/hadoop/hbase/io/hfile/HFileDataBlockEncoder.java
  src/main/java/org/apache/hadoop/hbase/io/hfile/HFileDataBlockEncoderImpl.java
  src/main/java/org/apache/hadoop/hbase/io/hfile/HFilePrettyPrinter.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/io/hfile/NoOpDataBlockEncoder.java
  src/main/java/org/apache/hadoop/hbase/mapreduce/LoadIncrementalHFiles.java
  src/main/java/org/apache/hadoop/hbase/regionserver/CompactSplitThread.java
  src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
  src/main/java/org/apache/hadoop/hbase/regionserver/MemStore.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/java/org/apache/hadoop/hbase/util/ByteBufferUtils.java
  src/main/java/org/apache/hadoop/hbase/util/CompoundBloomFilter.java
  src/main/ruby/hbase/admin.rb
  src/test/java/org/apache/hadoop/hbase/BROKE_TODO_FIX_TestAcidGuarantees.java
  src/test/java/org/apache/hadoop/hbase/HBaseTestCase.java
  src/test/java/org/apache/hadoop/hbase/HBaseTestingUtility.java
  src/test/java/org/apache/hadoop/hbase/HFilePerformanceEvaluation.java
  src/test/java/org/apache/hadoop/hbase/TestAcidGuarantees.java
  src/test/java/org/apache/hadoop/hbase/client/TestAdmin.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/TestHeapSize.java
  src/test/java/org/apache/hadoop/hbase/io/encoding/RedundantKVGenerator.java
  src/test/java/org/apache/hadoop/hbase/io/encoding/TestBufferedDataBlockEncoder.java
  src/test/java/org/apache/hadoop/hbase/io/encoding/TestChangingEncoding.java
  src/test/java/org/apache/hadoop/hbase/io/encoding/TestDataBlockEncoders.java
  src/test/java/org/apache/hadoop/hbase/io/encoding/TestEncodedSeekers.java
  src/test/java/org/apache/hadoop/hbase/io/encoding/TestLoadAndSwitchEncodeOnDisk.java
  src/test/java/org/apache/hadoop/hbase/io/encoding/TestUpgradeFromHFileV1ToEncoding.java
  src/test/java/org/apache/hadoop/hbase/io/hfile/CacheTestUtils.java
  src/test/java/org/apache/hadoop/hbase/io/hfile/TestCacheOnWrite.java
  src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFile.java
  src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileBlock.java
  src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileBlockIndex.java
  src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileDataBlockEncoder.java
  src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFilePerformance.java
  src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileSeek.java
  src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileWriterV2.java
  src/test/java/org/apache/hadoop/hbase/mapreduce/TestImportExport.java
  src/test/java/org/apache/hadoop/hbase/regionserver/CreateRandomStoreFile.java
  src/test/java/org/apache/hadoop/hbase/regionserver/DataBlockEncodingTool.java
  src/test/java/org/apache/hadoop/hbase/regionserver/EncodedSeekPerformanceTest.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/TestMultiColumnScanner.java
  src/test/java/org/apache/hadoop/hbase/regionserver/TestScanWithBloomError.java
  src/test/java/org/apache/hadoop/hbase/regionserver/TestSeekOptimizations.java
  src/test/java/org/apache/hadoop/hbase/regionserver/TestStoreFile.java
  src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestLogRolling.java
  src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALReplay.java
  src/test/java/org/apache/hadoop/hbase/util/LoadTestKVGenerator.java
  src/test/java/org/apache/hadoop/hbase/util/LoadTestTool.java
  src/test/java/org/apache/hadoop/hbase/util/MultiThreadedReader.java
  src/test/java/org/apache/hadoop/hbase/util/MultiThreadedWriter.java
  src/test/java/org/apache/hadoop/hbase/util/RestartMetaTest.java
  src/test/java/org/apache/hadoop/hbase/util/TestByteBufferUtils.java
  src/test/java/org/apache/hadoop/hbase/util/TestLoadTestKVGenerator.java
  src/test/java/org/apache/hadoop/hbase/util/TestMiniClusterLoadEncoded.java
  src/test/java/org/apache/hadoop/hbase/util/TestMiniClusterLoadParallel.java
  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-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, D447.3.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.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_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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