snapshot()

名称

snapshot - 获取快照

语法

db.snapshot(<snapType>,[cond],[sel],[sort])

db.snapshot(<snapType>,[SdbSnapshotOption])

类别

Sdb

描述

该函数用于获取指定快照，查看当前系统状态。

参数

Note:

• sel 参数是一个 json 结构，如：{字段名:字段值}，字段值一般指定为空串。sel 中指定的字段名在记录中存在，设置字段值不生效；不存在则返回 sel 中指定的字段名和字段值。
• 记录中字段值类型为数组，我们可以在 sel 中指定该字段名，用"."操作符加上双引号("")来引用数组元素。

返回值

函数执行成功时，将返回一个 SdbCursor 类型的对象。

函数执行失败时，将抛异常并输出错误信息。

错误

当异常抛出时，可以通过 getLastErrMsg() 获取错误信息或通过 getLastError() 获取错误码。更多错误处理可以参考常见错误处理指南。

版本

v2.0 及以上版本

示例

• 指定 snapType 的值为 SDB_SNAP_CONTEXTS

  > db.snapshot( SDB_SNAP_CONTEXTS )
  {
    "SessionID": "vmsvr1-cent-x64-1:11820:22",
    "Contexts": [
      {
        "ContextID": 8,
        "Type": "DUMP",
        "Description": "BufferSize:0",
        "DataRead": 0,
        "IndexRead": 0,
        "QueryTimeSpent": 0,
        "StartTimestamp": "2013-12-28-16.07.59.146399"
      }
    ]
  }
  {
    "SessionID": "vmsvr1-cent-x64-1:11830:22",
    "Contexts": [
      {
        "ContextID": 6,
        "Type": "DUMP",
        "Description": "BufferSize:0",
        "DataRead": 0,
        "IndexRead": 0,
        "QueryTimeSpent": 0,
        "StartTimestamp": "2013-12-28-16.07.59.147576"
      }
    ]
  }
  {
    "SessionID": "vmsvr1-cent-x64-1:11840:23",
    "Contexts": [
      {
        "ContextID": 7,
        "Type": "DUMP",
        "Description": "BufferSize:0",
        "DataRead": 0,
        "IndexRead": 0,
        "QueryTimeSpent": 0,
        "StartTimestamp": "2013-12-28-16.07.59.148603"
      }
    ]
  }

• 通过组名或组 ID 查询某个复制组的快照信息

  > db.snapshot( SDB_SNAP_CONTEXTS, { GroupName:'data1' } )
  > db.snapshot(SDB_SNAP_CONTEXTS,{GroupID:1000})
  {
    "SessionID": "vmsvr1-cent-x64-1:11820:22",
    "Contexts": [
      {
        "ContextID": 11,
        "Type": "DUMP",
        "Description": "BufferSize:0",
        "DataRead": 0,
        "IndexRead": 0,
        "QueryTimeSpent": 0,
        "StartTimestamp": "2013-12-28-16.13.57.864245"
      }
    ]
  }
  {
    "SessionID": "vmsvr1-cent-x64-1:11840:23",
    "Contexts": [
      {
        "ContextID": 10,
        "Type": "DUMP",
        "Description": "BufferSize:0",
        "DataRead": 0,
        "IndexRead": 0,
        "QueryTimeSpent": 0,
        "StartTimestamp": "2013-12-28-16.13.57.865103"
      }
    ]
  }

• 通过指定组名、主机名和服务名，或指定组 ID 和节点 ID查询某个节点的快照信息

  > db.snapshot( SDB_SNAP_CONTEXTS, { GroupName: 'data1', HostName: "vmsvr1-cent-x64-1", svcname: "11820" } )
  > db.snapshot(SDB_SNAP_CONTEXTS,{GroupID:1000,NodeID:1001})
  {
    "SessionID": "vmsvr1-cent-x64-1:11820:22",
    "Contexts": [
      {
        "ContextID": 11,
        "Type": "DUMP",
        "Description": "BufferSize:0",
        "DataRead": 0,
        "IndexRead": 0,
        "QueryTimeSpent": 0,
        "StartTimestamp": "2013-12-28-16.13.57.864245"
      }
    ]
  }

• 通过指定主机名和服务名查询某个节点的快照信息

  > db.snapshot( SDB_SNAP_CONTEXTS, { HostName: "ubuntu-200-043", svcname: "11820" } )
  {
    "NodeName": "ubuntu-200-043:11820",
    "SessionID": 18,
    "Contexts": [
      {
        "ContextID": 31,
        "Type": "DUMP",
        "Description": "IsOpened:1,HitEnd:0,BufferSize:0",
        "DataRead": 0,
        "IndexRead": 0,
        "QueryTimeSpent": 0,
        "StartTimestamp": "2016-10-27-17.53.45.042061"
      }
    ]
  }

• 返回未在 coord 聚集前的原始数据

  > db.snapshot( SDB_SNAP_DATABASE, { RawData: true } ,{ NodeName: null, GroupName: null, TotalDataRead: null } )
  {
    "NodeName": "ubuntu1604-yt:30000",
    "GroupName": "SYSCatalogGroup",
    "TotalDataRead": 276511
  }
  {
    "NodeName": "ubuntu1604-yt:20000",
    "GroupName": "db1",
    "TotalDataRead": 16542209
  }
  {
    "NodeName": "ubuntu1604-yt:40000",
    "GroupName": "db2",
    "TotalDataRead": 959
  }
  Return 3 row(s).