snapshot()

语法

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

枚举快照，快照是一种得到当前系统状态的命令。查看更多有关快照信息

参数描述

Note:

• snapType 字段的值请参考 快照类型。
• 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

返回游标对象，出错抛异常，并输出错误信息，可以通过getLastErrMsg()获取错误信息或通过getLastError()获取错误码。 关于错误处理可以参考常见错误处理指南。

错误

常见错误可参考错误码。

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 查询某个分区组的快照信息，如：

  > 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“组名+主机名+服务名”或“组 ID+节点 ID”查询某个节点的快照信息，如：

  > 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“主机名+服务名”查询某个节点的快照信息，如：

  > 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).