HBase Status Report - Hadoop Summit Europe 2014

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HBase 0.96+ A Report on the Current Status Lars George | EMEA Chief Architect

About Me

•  EMEA Chief Architect @ Cloudera •  ConsulDng on Hadoop projects (everywhere)

•  Apache CommiLer •  HBase and Whirr

•  O’Reilly Author •  HBase – The DefiniDve Guide

•  Now in Japanese!

•  Contact •  [email protected] •  @larsgeorge

日本語版も出ました!

The Content...

•  Version History •  Overview of new Features •  Summary

CONFIDENTIAL -‐ RESTRICTED

Version History A Timeline Overview

HBase Releases

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URL: hLp://s.apache.org/hbase-‐releases

HBase Releases – Issues Closed (JIRA)

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HBase Releases – Issues Closed (DisDnct)

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HBase Book?

I am trailing 0.92.0 by 800+ commits, including for example r1153634 | tedyu | 2011-08-03 21:59:48 +0200 ⤦

(Wed, 03 Aug 2011) | 2 lines

HBASE-3857 Change the HFile Format (Mikhail & Liyin)

…which is not “unimportant”. J I am working on an update!

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Coprocessors and more…

HBase 0.92

HBase 0.92 -‐ Highlights

•  682 issues addressed •  811 issues total in 0.92.x line •  New logo! (HBASE-‐4312) •  HFile v2 (HBASE-‐3857) •  Distributed Log Splilng (HBASE-‐1364) •  Enhanced Master UI

•  Major compacDon progress (HBASE-‐3900) •  Regions in transiDon (HBASE-‐4291) •  Tasks (HBASE-‐3839)

•  Slow Query Metrics (HBASE-‐4117)

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•  Coprocessors (HBASE-‐2000) •  Oneap cache (HBASE-‐4027) •  Online Table Schema Change (HBASE-‐1730) •  Regions Size from 256MB to 1GB (HBASE-‐4374) •  Hadoop 1 Support (HBASE-‐5125) •  Snappy Support (HBASE-‐3691) •  Keep last version with TTL (HBASE-‐4071) • MulDthreaded CompacDons (HBASE-‐4572)

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HFile v1 – HBase 0.90

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•  Previously the file layout was data blocks, meta blocks and then file metadata like indexes.

•  Each data block held a magic header and then the actual data sequenDally.

HFile v2 – HBase 0.92+

The 2nd version of HFile splits the indexes and Bloom filters up into a hierarchy and interleaves those with data blocks.

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The data block header now holds addiDonal info on the block itself.

Source: hLp://blog.cloudera.com/blog/2012/06/hbase-‐io-‐hfile-‐input-‐output/

Coprocessors: Observers

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Coprocessors: RPC Calls

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Slab Cache – Off-‐heap Block Cache

17 hLp://blog.cloudera.com/blog/2012/01/caching-‐in-‐hbase-‐slabcache/

•  The off-‐heap cache uses Java NIO’s Direct ByteBuffer structures

•  Uses its on slab allocaDon handling •  Does copy-‐on-‐read during access of data

•  Uses L2 cache and replaces OS buffer cache

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Performance Tuning…

HBase 0.94


•  420 issues addressed •  1394 issues total in 0.94.x line •  Read Caching Improvements (HBASE-‐5074) •  Seek OpDmizaDon

•  Bloom Filter for Delete Family (HBASE-‐4532) •  Lazy Seeks (HBASE-‐4465)

• Write to WAL OpDmizaDons •  WAL Compression (HBASE-‐4608)

•  Data Block Encoding of KeyValues (HBASE-‐4218) •  Improved HBaseFsck (HBASE-‐5128)

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•  Simplified Region Sizing (HBASE-‐4365) •  Smarter TransacDon SemanDcs

•  Atomic Put&Delete in One Call (HBASE-‐3584)

•  Snapshots (0.94.6) (HBASE-‐7360) •  Atomic Appends (HBASE-‐4102) • MulD Increment and Append (HBASE-‐2947) • More Aggressive Off-‐Peak CompacDons (HBASE-‐4463)

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•  Per Column Family Metrics (HBASE-‐4219) • MulD-‐row local transacDons (HBASE-‐5229)

•  Pluggable Split Key Policy (HBASE-‐5304)

•  Load balance regions by table (HBASE-‐3373) •  Also backported to 0.92.1

• Make CompacDon Code Pluggable (HBASE-‐6427) •  Deprecate HTablePool (0.94.11) (HBASE-‐6580) •  Canary Test Tool (HBASE-‐4393)

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Block Encoding

•  Allows to reduce data footprint in memory •  Only encodes the key porDon of a key/value pair •  Encoded keys stay encoded also during flushes •  Compression on top of encoding takes care of the values and remainder of key data

Example: •  Key length: 90B •  Value length: 8B

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Type Ra0o Key Compression 92% Total Compression 85% LZO on same data 85% LZO axer encoding 91%

hLps://issues.apache.org/jira/browse/HBASE-‐4218

Block Encoding: None

23 Source: hLp://blog.cloudera.com/blog/2012/06/hbase-‐io-‐hfile-‐input-‐output/

• With no encoding the Key/Value structures are stored verbaDm (with some overhead for lengths)

•  In the past you were advised to keep the “keys” short for that reason

Block Encoding: Prefix Encoding


•  The encoding patch added a new Cell abstracDon that allows for extra fields in a Key/Value

•  The fields are used to track necessary details for the encoding

Block Encoding: Diff Encoding


•  Apart from the prefix encoding there are other ways of encoding the keys

•  The diff encoding is one of such approaches

Block Encoding

•  Advantage of block encoding is faster decompression/decoding

•  20-‐80% faster than LZO

•  Also it allows to seek data sDll, which is not possible with compressed data

•  Penalty is a slightly slower read performance compared to non-‐encoded keys

•  Important is to watch the sizes and repeDDon of key data, encoding might not be useful for random data

26 hLps://issues.apache.org/jira/browse/HBASE-‐4218

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The Singularity

HBase 0.96


•  1219 issues addressed •  2243 issues total in 0.96.x line •  Improved Stability (HBASE-‐6241/6201)

•  ZK based Read/Write locks for table operaDons (HBASE-‐7305) •  Scalability Improvements (HBASE-‐8877)

•  Schema Storage (HBASE-‐8778) •  Log Cleaner for ReplicaDon Speed Up (HBASE-‐9208)

•  Mean-‐Time-‐To-‐Recovery (MTTR) Improvements (HBASE-‐5844/5926)

•  Distributed Log Replay (HBASE-‐7006) •  Dedicated WAL for System Table (HBASE-‐7213/8631)

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•  Operability Improvements •  Hooks for Health Scripts (HBASE-‐7399/7406) •  Trace Lagging Calls with HTrace (HBASE-‐9121)

•  Versioned RPCs and Metadata (Protobufs) (HBASE-‐3505) •  Parallel Seeks in Stores (HBASE-‐7495) •  Hadoop 1 and 2 Support

•  Secure Short Circuit Reads on H2 (HBASE-‐6783)

•  Namespaces Support (HBASE-‐8015) •  New Metrics v2 (HBASE-‐4050) •  Cell Interface vs KeyValue (HBASE-‐7162)

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•  No more ROOT table (HBASE-‐3171) •  Remove HFile v1 (HBASE-‐7660) •  Trie Data Block Encoding (HBASE-‐4676) •  Remove Client-‐side Row Locks (HBASE-‐7263/7315) •  CompacDon and Flush Improvements

(HBASE-‐7516/7763/6466/7678) (HBASE-‐7667/7110/7603/7519/7842)

•  Improved Default ConfiguraDon (HBASE-‐4657?) •  Client-‐side Type Library (HBASE-‐8089)

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•  Online Region Merging (HBASE-‐7403/8219) •  Bucket Cache Support (HBASE-‐7404) •  Remove older ICV Calls (HBASE-‐7032) •  New “Bootstrap” based UIs! (HBASE-‐6135) •  Remove Client-‐side Row Locks (HBASE-‐7263/7315) •  CompacDon and Flush Improvements

(HBASE-‐7516/7763/6466/7678) (HBASE-‐7667/7110/7603/7519/7842)

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— Michael Stack, HBase PMC Chair

Mean-‐Time-‐To-‐Recovery (MTTR)

•  Lot‘s of effort put into improve how long data might not be accessible during a region move

•  The offline period is made up of phases: •  a detecDon phase, •  a repair phase, •  reassignment, and finally, •  clients noDcing the data available in its new locaDon

•  Improvements in many of those areas •  Faster detecDon, efficient repair, parallel replay •  Dedicated WAL for system tables

33 hLps://blog.cloudera.com/blog/2013/10/hbase-‐0-‐96-‐0-‐released/

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Cell Level Security

HBase 0.98


•  1303 issues addressed •  1458 issues total in 0.98.x line •  Cell Level Security (HBASE-‐6222/7663/7662) •  Server-‐side EncrypDon (HBASE-‐7544) • WAL Throughput Improvements (HBASE-‐8755) •  Reverse Scanner (HBASE-‐4811) • MapReduce over Snapshot Files (HBASE-‐8369) •  Striped CompacDons (HBASE-‐7667) •  ThroLle ReplicaDon (HBASE-‐9501)

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Cell Level Security

•  Added HFile v3 which can store arbitrary metadata in a cell, called tags

•  Also extended ACL checks to apply to cell levels • With this visibility labels can be stored in tags •  An API and CLI tools are provided that are akin to Accumulo’s, axer which it is modeled

•  AddiDonal encrypDon of data at rest ensures further security of sensiDve data

36 hLps://blogs.apache.org/hbase/entry/hbase_cell_security

Visibility Labels

The API allows to set visibility by using expressions with “&”, “|”, and “!”, as well as “(“ and “)”, e.g. label set of { confidenDal, secret, topsecret, probaDonary } could be combined as

( secret | topsecret ) & !probationary

At runDme the expressions are evaluated against a user and then applied to each cell.

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The Future…

HBase 0.??

HBase Future

•  Not much is wriDng in stone yet • Master gets rewriLen and also META table handling

•  Build in consensus (HBASE-‐10296) •  Co-‐locate Master and META (HBASE-‐10569)

• MTTR is further extended into interesDng areas •  Read replicas (HBASE-‐10070)

It has to be seen when 1.0.0 is released and what it contains. Your opinion counts!

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Ques0ons?

@larsgeorge

HBase Status Report - Hadoop Summit Europe 2014

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