State of Cassandra 2011

Jonathan Ellis Apache Chair CTO DataStax

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Job Trends from Indeed.com

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•  Financial •  Social Media •  Advertising •  Entertainment •  Energy •  E-tail •  Health care •  Government

Customer and Verticals

Why?

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Why?  

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Why Cassandra?

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Why  Cassandra?  

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Better technology

•  Multi-master, multi-DC •  Linearly scalable •  Larger-than-memory datasets •  Best-in-class performance (not just writes!) •  Fully durable •  Integrated caching •  Tuneable consistency

Tunable Consistency

Level

ANY

ONE

LOCAL_QUORUM

QUORUM

ALL

WRITE READ Level

ONE

LOCAL_QUORUM

QUORUM

ALL

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Generalizes Easily to Multi-DC

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0.7

•  CREATE COLUMN FAMILY •  Expiring columns (TTL) •  Secondary (column) indexes •  Efficient streaming

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0.8

•  CQL •  Counters •  Automatic memtable tuning •  New bulk load interface

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A performance retrospective

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Road to 1.0 October 8, 2011

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Theme: polish

•  Repair •  Compaction •  Optimize reads for update-heavy workloads •  CQL 1.1

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Repair

•  Consistency is checked per-ColumnFamily but data is transferred per-Keyspace

•  Merkle trees requests are sent en masse, but may not execute start at the same time

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Compression •  Rows-per-block or blocks-per-row

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Read Performance: Compaction

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Level-based Compaction •  SSTables are non-overlapping within a level •  Bounds the number that can contain a given row

L2: 1000 MB

L1: 100 MB

L0: newly flushed

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Read performance: maxtimestamp

•  Sort sstables by maximum (client-provided) timestamp

•  Only merge sstables until we have the columns request

•  Allows pre-merging highly fragmented rows without waiting for compaction

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CQL

cqlsh> SELECT * FROM users WHERE state='UT' AND birth_date > 1970;!        KEY | birth_date |         full_name | state |  bsanderson |       1975 | Brandon Sanderson |    UT |  

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CQL 1.1

•  ALTER •  Counter support •  TTL support •  Compound columns •  Prepared statements

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Post-1.0 •  Ease of use

• Ease of use

• Ease of use

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Post-1.0 features

•  “Native” CQL transport •  Triggers •  Entity groups •  Smarter range queries

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Brisk •  Analytics for your

realtime data without ETL

•  Widens scope of Cassandra’s applicability

•  Also: Solandra

Questions

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Ques/ons?