Cassandra112入门指南(单节点)

Cassandra1.1.2入门指南Cassandraisahighlyscalable,eventuallyconsistent,distributed,structuredkey-valuestore.Cassandra是高扩展性的、最终一致性的、分布式的、结构化的key/value存储系统。Formoreinformationsee:///:///cassandra/Projectdescription-------------------CassandrabringstogetherthedistributedsystemstechnologiesfromDynamoandthedatamodelfromGoogle'sBigTable.LikeDynamo,Cassandraiseventuallyconsistent.LikeBigTable,CassandraprovidesaColumnFamily-baseddatamodelricherthantypicalkey/valuesystems.Cassandra结合了源自Dynamo的分布式系统技术〔存储模型〕与源自GoogleBigTable的数据组织结构和访问控制技术〔数据模型〕。Cassandra采用了Dynamo的最终一致性原那么，采用了BigTable的基于ColumnFamily的数据模型〔优于典型的key/value系统数据模型〕。keyspace类似于关系数据库中的database。ColumnFamily类似于关系数据库中的关系relation。key类似于关系数据库中的主键primarykey。column类似于关系数据库中的列名columnname。value类似于关系数据库中一个行列交汇处的值value。Requirements------------*Java>=1.6(OpenJDKandSunhavebeentested)Gettingstarted---------------Thisshortguidewillwalkyouthroughgettingabasiconenodeclusterupandrunning,anddemonstratesomesimplereadsandwrites.构建并运行只有一个节点的集群，然后演示简单的读写。在Linux下执行命令如下：*tar-zxvfapache-cassandra-$VERSION.tar.gz*cdapache-cassandra-$VERSION*sudomkdir-p/var/log/cassandra*sudochown-R`whoami`/var/log/cassandra*sudomkdir-p/var/lib/cassandra*sudochown-R`whoami`/var/lib/cassandraNote:Thesampleconfigurationfilesinconf/determinethefile-systemlocationsCassandrausesforlogginganddatastorage.Youarefreetochangethesetosuityourownenvironmentandadjustthepathnamesusedhereaccordingly.$cassandra_HOME/conf/目录下的cassandra.yaml配置文件设置了用于记录日志和数据存储的文件系统的位置。可以任意修改到其他路径。#directorieswhereCassandrashouldstoredataondisk.data_file_directories:-/var/lib/cassandra/data#commitlogcommitlog_directory:/var/lib/cassandra/commitlog补充：Linux下执行bin/cassandra启动Cassandra之前，需要设置如下环境变量，否那么会抛出NoClassDefFoundError等异常：#CLASSPATH--AJavaclasspathcontainingeverythingnecessarytorun. Java类路径，包含运行所需的所有jar(通过bin/cassandra.in.sh设置)#JVM_OPTS--AdditionalargumentstotheJVMforheapsize,etc JVM的其他参数，如堆大小等(通过conf/cassandra-env.sh设置，执行bin/cassandra会调用该脚本)。#CASSANDRA_CONF--DirectorycontainingCassandraconfigurationfiles. Cassandra配置文件目录(通过bin/cassandra.in.sh设置)使环境变量立刻生效：sourcebin/cassandra.in.sh查看环境变量： echo$CLASSPATHNowthatwe'reready,let'sstartitup!Linux下翻开终端窗口，通过脚本启动Cassandra，执行如下：*bin/cassandra-fUnix:Runningthestartupscriptwiththe-fargumentwillcauseCassandratoremainintheforegroundandlogtostandardout.注意：Linux下启动Cassandra使用-f参数，可以使Cassandra前台运行，以方便查看输出日志。其他还有如下两个参数：#-p<filename>:logthepidtoafile(usefultokillitlater) 将Cassandra的进程ID〔pid〕记录到日志文件〔后续可以通过kill<pid>停止Cassandra〕#-v:printversionstringandexit 打印出版本信息并停止Windows:bin\cassandra.batrunsintheforegroundbydefault.ToinstallCassandraasaWindowsservice,downloadProcrunfrom:///daemon/procrun.html,setthePRUNSRVenvironmentvariabletothefullpathofprunsrv(e.g.,C:\procrun\prunsrv.exe),andrun"bin\cassandra.batinstall".Similarly,"uninstall"willremovetheservice.Nowlet'strytoreadandwritesomedatausingthecommandlineclient.下面就可以使用命令行客户端读写数据了。翻开新的终端窗口，执行如下命令：*bin/cassandra-cli--hostlocalhostThecommandlineclientisinteractivesoifeverythingworkedyoushouldbesittinginfrontofaprompt...该命令行客户端具有交互性，如果一切正常，将会出现如下提示。Connectedto:"TestCluster"onlocalhost/9160WelcometocassandraCLI.Type'help;'or'?'forhelp.Type'quit;'or'exit;'toquit.[default@unknown]Asthebannersays,youcanuse'help;'or'?'toseewhattheCLIhastooffer,and'quit;'or'exit;'whenyou'vehadenoughfun.Butletstrysomethingslightlymoreinteresting...在出现的提示符后面执行如下操作：[default@unknown]createkeyspaceKeyspace1;ece86bde-dc55-11df-8240-e700f669bcfc[default@unknown]useKeyspace1;Authenticatedtokeyspace:Keyspace1[default@Keyspace1]createcolumnfamilyUserswithcomparator=UTF8Typeanddefault_validation_class=UTF8Typeandkey_validation_class=UTF8Type;737c7a71-dc56-11df-8240-e700f669bcfc[default@KS1]setUsers[jsmith][first]='John';Valueinserted.[default@KS1]setUsers[jsmith][last]='Smith';Valueinserted.[default@KS1]setUsers[jsmith][age]=long(42);Valueinserted.[default@KS1]getUsers[jsmith];=>(column=last,value=Smith,timestamp=1287604215498000)=>(column=first,value=John,timestamp=1287604214111000)=>(column=age,value=42,timestamp=1287604216661000)Returned3results.Ifyoursessionlookssimilartowhat'sabove,congrats,yoursinglenodeclusterisoperational!Butwhatexactlywasallofthat?Let'sbreakitdownintopiecesandsee.setUsers[jsmith][first]='John';\\\\\\_key\\_value\\_column\_columnfamilyDatastoredinCassandraisassociatedwithacolumnfamily(Users),whichinturnisassociatedwithakeyspace(Keyspace1).Intheexampleabove,wesetthevalue'John'inthe'first'columnforkey'jsmith'.FormoreinformationontheCassandradatamodelbesuretocheckout:///cassandra/DataModelWondering