Zookeeper基本數據模型

ZooKeeper基本數據模型

3.1 基本數據模型介紹

• zk的數據模型也能夠理解爲linux/unix的文件目錄: /usr/local/...
• 每個節點都稱之爲znode, 它能夠有子節點, 也能夠有數據
• 每一個節點分爲臨時節點和永久節點,臨時節點在客戶端斷開後消失
• 每個zk節點都有各自的版本號, 能夠經過命令行來顯示節點信息
• 每當節點數據發生變化, 那麼該節點的版本號會累加(樂觀鎖)
• 刪除/修改過期節點, 版本號不匹配會報錯
• 每一個zk節點存儲的數據不宜過大, 幾k便可
• 節點能夠設置權限acl, 能夠經過權限來限制用戶的訪問

3.2 ZooKeeper數據模型的基本操做

• 客戶端鏈接

  • $ZOOKEEPER_HOME/bin 運行zkServer.sh start 開啓zookeeper

  • 進入客戶端

    ./zkCli.sh
    
    2018-12-29 02:23:22,904 [myid:] - INFO  [main-SendThread(localhost:2181):ClientCnxn$SendThread@1235] - Session establishment complete on server localhost/0:0:0:0:0:0:0:1:2181, sessionid = 0x167f60ba5ea0002, negotiated timeout = 30000
    
    WATCHER::
    
    WatchedEvent state:SyncConnected type:None path:null
    [zk: localhost:2181(CONNECTED) 0]

    • ls 列出目錄 help 查看幫助

    WatchedEvent state:SyncConnected type:None path:null
    [zk: localhost:2181(CONNECTED) 0] ls /
    [zookeeper]
    [zk: localhost:2181(CONNECTED) 1] ls /zookeeper
    [quota]
    [zk: localhost:2181(CONNECTED) 2] ls /zookeeper/quota
    []
    [zk: localhost:2181(CONNECTED) 3] help
    ZooKeeper -server host:port cmd args
            stat path [watch]
            set path data [version]
            ls path [watch]
            delquota [-n|-b] path
            ls2 path [watch]
            setAcl path acl
            setquota -n|-b val path
            history
            redo cmdno
            printwatches on|off
            delete path [version]
            sync path
            listquota path
            rmr path
            get path [watch]
            create [-s] [-e] path data acl
            addauth scheme auth
            quit
            getAcl path
            close
            connect host:port

• 查看znode結構

  • ls 列出目錄 help 查看幫助

    WatchedEvent state:SyncConnected type:None path:null
    [zk: localhost:2181(CONNECTED) 0] ls /
    [zookeeper]
    [zk: localhost:2181(CONNECTED) 1] ls /zookeeper
    [quota]
    [zk: localhost:2181(CONNECTED) 2] ls /zookeeper/quota
    []
    [zk: localhost:2181(CONNECTED) 3] help
    ZooKeeper -server host:port cmd args
            stat path [watch]
            set path data [version]
            ls path [watch]
            delquota [-n|-b] path
            ls2 path [watch]
            setAcl path acl
            setquota -n|-b val path
            history
            redo cmdno
            printwatches on|off
            delete path [version]
            sync path
            listquota path
            rmr path
            get path [watch]
            create [-s] [-e] path data acl
            addauth scheme auth
            quit
            getAcl path
            close
            connect host:port

• 關閉客戶端鏈接 ctrl+c