InMemeryWorkspace的效率测试结果

之前的文章提到创建各类createworkspace的方法（源于esri网站），里面有个特别的接口是InMemeryWorkspace，即内存GeoDatabase模型对象，主要是用于提高效率的，那今天就写一下创建要素（创建100000个点对象，相同坐标）的效率差异

 

基于文件的用Persoanl GeoDatabase格式，即mdb

测试环境：cpu－pentium M 1.5G，内存－1G，硬盘－5400转

开发环境：vba

 

下面提供完成测试代码及测试结果

 

'创建基于文件的要素类及数据
Public Sub CreateFilePolygonFeatureClass()
    Dim pworkspaceFactory As IWorkspaceFactory
    Set pworkspaceFactory = New AccessWorkspaceFactory
   
    Dim pworkspace As IWorkspace
    Set pworkspace = pworkspaceFactory.OpenFromFile("c:\test.mdb", 0)
   
    Dim pFeatureWorkspace As IFeatureWorkspace
    Set pFeatureWorkspace = pworkspace
   
    Dim pFeatureClass As IFeatureClass
    Set pFeatureClass = createWorkspaceFeatureClass(pFeatureWorkspace, "testlayer", esriFTSimple, esriGeometryPoint)
   
    Dim pFeatureCursor As IFeatureCursor
    Dim pFeature As IFeature
    Dim pFeatureBuffer As IFeatureBuffer
   
    Set pFeatureCursor = pFeatureClass.Insert(True)
    Set pFeatureBuffer = pFeatureClass.CreateFeatureBuffer
   
    Dim i As Long
    Dim pPoint As IPoint
    Dim l As Long
    Debug.Print Now
    For i = 1 To 100000
        Set pPoint = New Point
        pPoint.PutCoords 100, 200
        Set pFeatureBuffer.Shape = pPoint
        pFeatureCursor.InsertFeature pFeatureBuffer
        l = l + 1
        If l Mod 1000 = 0 Then
            pFeatureCursor.Flush
        End If
        Set pPoint = Nothing
    Next i
    pFeatureCursor.Flush
    Debug.Print Now
   
    Dim pmxdoc As IMxDocument
    Set pmxdoc = ThisDocument
    Dim pmap As IMap
    Set pmap = pmxdoc.FocusMap
    Dim pfeaturelayer As IFeatureLayer
    Set pfeaturelayer = New FeatureLayer
    Set pfeaturelayer.FeatureClass = pFeatureClass
    pmap.AddLayer pfeaturelayer
End Sub

'创建基于内存的要素类及数据
Public Sub CreateMemeryPolygonFeatureClass()
    Dim pworkspaceFactory As IWorkspaceFactory
    Set pworkspaceFactory = New AccessWorkspaceFactory
   
    Dim pworkspace As IWorkspace
    Set pworkspace = CreateInMemoryWorkspace
   
    Dim pFeatureWorkspace As IFeatureWorkspace
    Set pFeatureWorkspace = pworkspace
   
    Dim pFeatureClass As IFeatureClass
    Set pFeatureClass = createWorkspaceFeatureClass(pFeatureWorkspace, "testlayer", esriFTSimple, esriGeometryPoint)
   
    Dim pFeatureCursor As IFeatureCursor
    Dim pFeature As IFeature
    Dim pFeatureBuffer As IFeatureBuffer
   
    Set pFeatureCursor = pFeatureClass.Insert(True)
    Set pFeatureBuffer = pFeatureClass.CreateFeatureBuffer
   
    Dim i As Long
    Dim pPoint As IPoint
    Dim l As Long
    Debug.Print Now
    For i = 1 To 100000
        Set pPoint = New Point
        pPoint.PutCoords 100, 200
        Set pFeatureBuffer.Shape = pPoint
        pFeatureCursor.InsertFeature pFeatureBuffer
        l = l + 1
        If l Mod 1000 = 0 Then
            pFeatureCursor.Flush
        End If
        Set pPoint = Nothing
    Next i
    pFeatureCursor.Flush
    Debug.Print Now
   
    Dim pmxdoc As IMxDocument
    Set pmxdoc = ThisDocument
    Dim pmap As IMap
    Set pmap = pmxdoc.FocusMap
    Dim pfeaturelayer As IFeatureLayer
    Set pfeaturelayer = New FeatureLayer
    Set pfeaturelayer.FeatureClass = pFeatureClass
    pmap.AddLayer pfeaturelayer

 

End Sub

'创建内存工作空间对象

Public Function CreateInMemoryWorkspace() As IWorkspace
    Dim pworkspaceFactory As IWorkspaceFactory
    Set pworkspaceFactory = New InMemoryWorkspaceFactory
   
    Dim pworkspaceName As IWorkspaceName
    Set pworkspaceName = pworkspaceFactory.Create("", "MyWorkspace", Nothing, 0)
   
    Dim pName As IName
    Set pName = pworkspaceName
   
    Dim pworkspace As IWorkspace
    Set pworkspace = pName.Open()
   
    Set CreateInMemoryWorkspace = pworkspace
End Function

 

'创建要素类

Public Function createWorkspaceFeatureClass(featWorkspace As IFeatureWorkspace, _
                                            Name As String, _
                                            featType As esriFeatureType, _
                                            Optional geomType As esriGeometryType = esriGeometryPoint, _
                                            Optional pfields As IFields, _
                                            Optional pCLSID As UID, _
                                            Optional pCLSEXT As UID, _
                                            Optional ConfigWord As String = "" _
                                            ) As IFeatureClass
 
  On Error GoTo EH
 
  Set createWorkspaceFeatureClass = Nothing
  If featWorkspace Is Nothing Then Exit Function
  If Name = "" Then Exit Function
 
  If (pCLSID Is Nothing) Or IsMissing(pCLSID) Then
    Set pCLSID = Nothing
    Set pCLSID = New UID
   
    Select Case featType
      Case esriFTSimple
        pCLSID.Value = "esriGeoDatabase.Feature"
        If geomType = esriGeometryLine Then geomType = esriGeometryPolyline
      Case esriFTSimpleJunction
        geomType = esriGeometryPoint
        pCLSID.Value = "esriGeoDatabase.SimpleJunctionFeature"
      Case esriFTComplexJunction
        pCLSID.Value = "esriGeoDatabase.ComplexJunctionFeature"
      Case esriFTSimpleEdge
        geomType = esriGeometryPolyline
        pCLSID.Value = "esriGeoDatabase.SimpleEdgeFeature"
      Case esriFTComplexEdge
        geomType = esriGeometryPolyline
        pCLSID.Value = "esriGeoDatabase.ComplexEdgeFeature"
      Case esriFTAnnotation
        Exit Function
    End Select
  End If
 
  If (pfields Is Nothing) Or IsMissing(pfields) Then
    Dim pFieldsEdit As IFieldsEdit
    Set pFieldsEdit = New Fields
   
    Dim pGeomDef As IGeometryDef
    Set pGeomDef = New GeometryDef
    Dim pGeomDefEdit As IGeometryDefEdit
    Set pGeomDefEdit = pGeomDef
   
    Dim pSR As ISpatialReference
    Set pSR = New UnknownCoordinateSystem
    pSR.SetDomain 0, 21474.83645, 0, 21474.83645
    pSR.SetFalseOriginAndUnits 0, 0, 100000
   
    With pGeomDefEdit
      .GeometryType = geomType
      .GridCount = 1
      .GridSize(0) = 10
      .AvgNumPoints = 2
      .HasM = False
      .HasZ = False
      Set .SpatialReference = pSR
    End With
   
    Dim pField As IField
    Dim pFieldEdit As IFieldEdit
    Set pField = New Field
    Set pFieldEdit = pField
   
    pFieldEdit.Name = "SHAPE"
    pFieldEdit.AliasName = "GEOMETRY"
    pFieldEdit.Type = esriFieldTypeGeometry
    Set pFieldEdit.GeometryDef = pGeomDef
    pFieldsEdit.AddField pField
   
    Set pField = New Field
    Set pFieldEdit = pField
    pFieldEdit.Name = "OBJECTID"
    pFieldEdit.AliasName = "object identifier"
    pFieldEdit.Type = esriFieldTypeOID
    pFieldsEdit.AddField pField

 

    Set pfields = pFieldsEdit
  End If
 
  If (pCLSEXT Is Nothing) Or IsMissing(pCLSEXT) Then
    Set pCLSEXT = Nothing
  End If
 
  Dim strShapeFld As String
  Dim j As Integer
  For j = 0 To pfields.FieldCount - 1
    If pfields.Field(j).Type = esriFieldTypeGeometry Then
      strShapeFld = pfields.Field(j).Name
    End If
  Next
 
  Set createWorkspaceFeatureClass = featWorkspace.CreateFeatureClass(Name, pfields, pCLSID, _
                             pCLSEXT, featType, strShapeFld, ConfigWord)
 
  Exit Function
EH:
    MsgBox Err.Description, vbInformation, "createWorkspaceFeatureClass"
End Function

结果：基于文件的耗时为24秒（输出文件大小为25M），基于内存的耗时为0.3秒。我想主要的差异来自于写磁盘，如果磁盘的转速提高，应该写入文件的速度会提高，服务器硬盘有15000转的了，可以提高2倍，但仍不如基于内存的

 

还有个简单的地方可以看出两者差异，就是在arcmap打开属性表，移动到最后一条记录，用内存方式的速度要比文件方式的快些，但优势不明显，不过数据量和属性字段增加后优势会比较明显

 

因为基于内存的数据模型的使用与基于文件数据模型的使用没有差别，所以在处理大数据量、大循环或复杂的空间搜索时，建议使用内存数据模型