book

Cassandra: The Definitive Guide

by Eben Hewitt

November 2010

Intermediate to advanced

328 pages

9h 38m

English

O'Reilly Media, Inc.

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Why Apache Cassandra?Is This Book for You?What’s in This Book?Finding Out MoreConventions Used in This BookUsing Code ExamplesSafari® EnabledHow to Contact UsAcknowledgments
What’s Wrong with Relational Databases?A Quick Review of Relational DatabasesRDBMS: The Awesome and the Not-So-MuchTransactions, ACID-ity, and two-phase commitSchemaSharding and shared-nothing architectureSummaryWeb ScaleThe Cassandra Elevator PitchCassandra in 50 Words or LessDistributed and DecentralizedElastic ScalabilityHigh Availability and Fault ToleranceTuneable ConsistencyBrewer’s CAP TheoremRow-OrientedSchema-FreeHigh PerformanceWhere Did Cassandra Come From?Use Cases for CassandraLarge DeploymentsLots of Writes, Statistics, and AnalysisGeographical DistributionEvolving ApplicationsWho Is Using Cassandra?Summary
Installing the BinaryExtracting the DownloadWhat’s In There?Building from SourceAdditional Build TargetsBuilding with MavenRunning CassandraOn WindowsOn LinuxStarting the ServerRunning the Command-Line Client InterfaceBasic CLI CommandsHelpConnecting to a ServerDescribing the EnvironmentCreating a Keyspace and Column FamilyWriting and Reading DataSummary
The Relational Data ModelA Simple IntroductionClustersKeyspacesColumn FamiliesColumn Family OptionsColumnsWide Rows, Skinny RowsColumn SortingSuper ColumnsComposite KeysDesign Differences Between RDBMS and CassandraNo Query LanguageNo Referential IntegritySecondary IndexesSorting Is a Design DecisionDenormalizationDesign PatternsMaterialized ViewValueless ColumnAggregate KeySome Things to Keep in MindSummary
Data DesignHotel App RDBMS DesignHotel App Cassandra DesignHotel Application CodeCreating the DatabaseLoading the schemaData StructuresGetting a ConnectionPrepopulating the DatabaseThe Search ApplicationTwissandraSummary
System KeyspacePeer-to-PeerGossip and Failure DetectionAnti-Entropy and Read RepairMemtables, SSTables, and Commit LogsHinted HandoffCompactionBloom FiltersTombstonesStaged Event-Driven Architecture (SEDA)Managers and ServicesCassandra DaemonStorage ServiceMessaging ServiceHinted Handoff ManagerSummary
KeyspacesCreating a Column FamilyTransitioning from 0.6 to 0.7ReplicasReplica Placement StrategiesSimple StrategyOld Network Topology StrategyNetwork Topology StrategyReplication FactorIncreasing the Replication FactorPartitionersRandom PartitionerOrder-Preserving PartitionerCollating Order-Preserving PartitionerByte-Ordered PartitionerSnitchesSimple SnitchPropertyFileSnitchCreating a ClusterChanging the Cluster NameAdding Nodes to a ClusterMultiple Seed NodesDynamic Ring ParticipationSecurityUsing SimpleAuthenticatorProgrammatic AuthenticationUsing MD5 EncryptionProviding Your Own AuthenticationMiscellaneous SettingsAdditional ToolsViewing KeysImporting Previous ConfigurationsSummary

Query Differences Between RDBMS and CassandraNo Update QueryRecord-Level Atomicity on WritesNo Server-Side Transaction SupportNo Duplicate KeysBasic Write PropertiesConsistency LevelsBasic Read PropertiesThe APIRanges and SlicesSetup and Inserting DataUsing a Simple GetSeeding Some ValuesSlice PredicateGetting Particular Column Names with Get SliceGetting a Set of Columns with Slice RangeCountsReversedGetting All Columns in a RowGet Range SlicesMultiget SliceDeletingBatch MutatesBatch DeletesRange GhostsProgrammatically Defining Keyspaces and Column FamiliesSummary
Basic Client APIThriftThrift Support for JavaExceptionsThrift SummaryAvroAvro Ant TargetsAvro SpecificationAvro SummaryA Bit of GitConnecting Client NodesClient ListRound-Robin DNSLoad BalancerCassandra Web ConsoleHector (Java)FeaturesThe Hector APIHectorSharp (C#)ChirperChiton (Python)Pelops (Java)Kundera (Java ORM)Fauna (Ruby)Summary
LoggingTailingGeneral TipsFollowing alongWarning signsOverview of JMX and MBeansMBeansIntegrating JMXInteracting with Cassandra via JMXCassandra’s MBeansorg.apache.cassandra.concurrentorg.apache.cassandra.dborg.apache.cassandra.gmsorg.apache.cassandra.serviceStorageServiceStreamingServiceCustom Cassandra MBeansRuntime Analysis ToolsHeap Analysis with JMX and JHATDetecting Thread ProblemsHealth CheckSummary
Getting Ring InformationInfoRingRange TokensGetting StatisticsUsing cfstatsUsing tpstatsBasic MaintenanceRepairFlushCleanupSnapshotsTaking a SnapshotClearing a SnapshotLoad-Balancing the Clusterloadbalance and streamsDecommissioning a NodeUpdating NodesRemoving TokensCompaction ThresholdChanging Column Families in a Working ClusterSummary
Data StorageReply TimeoutCommit LogsMemtablesConcurrencyCachingBuffer SizesUsing the Python Stress TestGenerating the Python Thrift InterfacesGetting ThriftRunning the Python Stress TestStartup and JVM SettingsTuning the JVMSummary
What Is Hadoop?Working with MapReduceCassandra Hadoop Source PackageRunning the Word Count ExampleOutputting Data to CassandraHadoop StreamingTools Above MapReducePigHiveCluster ConfigurationUse CasesRaptr.com: Keith ThornhillImagini: Dave GardnerSummary
Nonrelational DatabasesObject DatabasesXML DatabasesSoftwareAG TaminoeXistOracle Berkeley XML DBMarkLogic ServerApache XindiceSummaryDocument-Oriented DatabasesIBM LotusApache CouchDBMongoDBRiakGraph DatabasesFlockDBNeo4JKey-Value Stores and Distributed HashtablesAmazon DynamoProject VoldemortRedisColumnar DatabasesGoogle BigtableHBaseHypertablePolyglot PersistenceSummary

Content preview from Cassandra: The Definitive Guide

Chapter 5. The Cassandra Architecture

In this chapter, we examine several aspects of Cassandra’s internal design in order to understand how it does its job. We consider the peer-to-peer design and its corresponding gossip protocol, as well as what Cassandra does on read and write requests, and examine how these choices affect architectural considerations such as scalability, durability, availability, manageability, and more. We also discuss Cassandra’s adoption of a Staged Event-Driven Architecture, which acts as the platform for request delegation.

The Cassandra architecture is very sophisticated and relies on the use of several different theoretical constructs. It is hard to discuss any one new term without referencing other terms we probably also haven’t met yet. This can be frustrating, which is why I’ve included the Glossary in the back of the book for you to refer to.

System Keyspace

Cassandra has an internal keyspace called system that it uses to store metadata about the cluster to aid in operations. In Microsoft SQL Server, two meta-databases are maintained: master and tempdb. The master is used to keep information about disk space, usage, system settings, and general server installation notes; the tempdb is used as a workspace to store intermediate results and perform general tasks. The Oracle database always has a tablespace called SYSTEM, used for similar purposes. The Cassandra system keyspace is used much like these.

Specifically, the system keyspace stores metadata for ...