VERSION 5.00
Begin VB.Form frmChunkSize 
   Caption         =   "chunksize"
   ClientHeight    =   7890
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   14625
   LinkTopic       =   "Form1"
   ScaleHeight     =   7890
   ScaleWidth      =   14625
   StartUpPosition =   1  'CenterOwner
   Begin VB.CommandButton cmdGetImage 
      Caption         =   "Display Image"
      BeginProperty Font 
         Name            =   "MS Sans Serif"
         Size            =   9.75
         Charset         =   0
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   495
      Left            =   10560
      TabIndex        =   11
      Top             =   6960
      Width           =   1575
   End
   Begin VB.Frame Frame2 
      Caption         =   "Result"
      BeginProperty Font 
         Name            =   "Times New Roman"
         Size            =   12.75
         Charset         =   0
         Weight          =   700
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   1455
      Left            =   8400
      TabIndex        =   8
      Top             =   4800
      Width           =   5535
      Begin VB.Label lblRoundTrips 
         BeginProperty Font 
            Name            =   "Times New Roman"
            Size            =   12
            Charset         =   0
            Weight          =   400
            Underline       =   0   'False
            Italic          =   0   'False
            Strikethrough   =   0   'False
         EndProperty
         Height          =   255
         Left            =   2400
         TabIndex        =   13
         Top             =   960
         Width           =   2175
      End
      Begin VB.Label lblTimeTaken 
         BeginProperty Font 
            Name            =   "Times New Roman"
            Size            =   12
            Charset         =   0
            Weight          =   400
            Underline       =   0   'False
            Italic          =   0   'False
            Strikethrough   =   0   'False
         EndProperty
         Height          =   375
         Left            =   1560
         TabIndex        =   12
         Top             =   480
         Width           =   3735
      End
      Begin VB.Label Label5 
         Caption         =   "No. of  Round Trips = "
         BeginProperty Font 
            Name            =   "Times New Roman"
            Size            =   12.75
            Charset         =   0
            Weight          =   400
            Underline       =   0   'False
            Italic          =   0   'False
            Strikethrough   =   0   'False
         EndProperty
         Height          =   375
         Left            =   120
         TabIndex        =   10
         Top             =   960
         Width           =   2295
      End
      Begin VB.Label label 
         Caption         =   "Time Taken ="
         BeginProperty Font 
            Name            =   "Times New Roman"
            Size            =   12.75
            Charset         =   0
            Weight          =   400
            Underline       =   0   'False
            Italic          =   0   'False
            Strikethrough   =   0   'False
         EndProperty
         Height          =   255
         Left            =   120
         TabIndex        =   9
         Top             =   480
         Width           =   1455
      End
   End
   Begin VB.OptionButton optchunk 
      Caption         =   "Chunk Size (in bytes)"
      BeginProperty Font 
         Name            =   "Times New Roman"
         Size            =   12.75
         Charset         =   0
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   495
      Left            =   8520
      TabIndex        =   5
      Top             =   3840
      Width           =   3135
   End
   Begin VB.OptionButton optValue 
      Caption         =   "Value Property"
      BeginProperty Font 
         Name            =   "Times New Roman"
         Size            =   12.75
         Charset         =   0
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   495
      Left            =   8520
      TabIndex        =   4
      Top             =   3360
      Value           =   -1  'True
      Width           =   2535
   End
   Begin VB.ComboBox cboSelectProduct 
      BeginProperty Font 
         Name            =   "Verdana"
         Size            =   9
         Charset         =   0
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   330
      Left            =   2280
      Style           =   2  'Dropdown List
      TabIndex        =   0
      Top             =   1680
      Width           =   3255
   End
   Begin VB.Frame Frame1 
      Caption         =   "Chunk Size"
      BeginProperty Font 
         Name            =   "Times New Roman"
         Size            =   12.75
         Charset         =   0
         Weight          =   700
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   1455
      Left            =   8400
      TabIndex        =   6
      Top             =   3000
      Width           =   5535
      Begin VB.TextBox txtChunkSize 
         Enabled         =   0   'False
         Height          =   375
         Left            =   3840
         TabIndex        =   7
         Text            =   "100"
         Top             =   840
         Width           =   1575
      End
   End
   Begin VB.Label Label2 
      Caption         =   "Update Product Image"
      BeginProperty Font 
         Name            =   "Times New Roman"
         Size            =   18.75
         Charset         =   0
         Weight          =   700
         Underline       =   -1  'True
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      ForeColor       =   &H00FF0000&
      Height          =   495
      Left            =   5760
      TabIndex        =   3
      Top             =   360
      Width           =   4215
   End
   Begin VB.Label Label1 
      Caption         =   "Select Product"
      BeginProperty Font 
         Name            =   "Times New Roman"
         Size            =   14.25
         Charset         =   0
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   495
      Left            =   240
      TabIndex        =   2
      Top             =   1680
      Width           =   1815
   End
   Begin VB.Image imgProduct 
      BorderStyle     =   1  'Fixed Single
      Height          =   4335
      Left            =   2280
      Stretch         =   -1  'True
      Top             =   2520
      Width           =   5535
   End
   Begin VB.Label Label3 
      Caption         =   "Product Image"
      BeginProperty Font 
         Name            =   "Times New Roman"
         Size            =   14.25
         Charset         =   0
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   495
      Left            =   240
      TabIndex        =   1
      Top             =   2520
      Width           =   1815
   End
End
Attribute VB_Name = "frmChunkSize"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
'*************************************************************************************
' @author   Jagriti
' @version  1.0
'
' Development Environment       : MS-Visual Basic 6.0
' Name of the Application       : chunkSizeSample.vbp
' Creation/Modification History :
'
' Jagriti       23-Jul-2001       Created
'
' Overview of Application       :
'
' This sample aims at demonstrating the use of ADO ChunkSize property versus ADO Value
' property. With ADO Value Property the whole column value is fetched in a single
' network roundtrip from the database, though the data retrieval performance is
' always high but this requires more memory at the client side. So it is not feasible
' for huge column data like LOBs. With ADO ChunkSize Property the data is retrieved in
' chunks of bytes and the number of roundtrips made is equal to(size of data/ChunkSize).
' This requires less memory at client side but degrades the performance as more
' roundtrips to the database. Therefore by providing an optimized value of chunk size
' helps in efficently utilizing resources where system memory is limited.
'
' When this application runs, a list of products populated from Product_Information
' database table appears. The user can select a product from the list. Then choose the
' option of either Value Property or ChunkSize Property. If Value property is chosen then
' directly the "Display Image" button can be pressed and time taken to get the image can be
' noted. Else if ChunkSize property is chosen then a value for ChunkSize can be entered
' and the time taken and No. of round trips can be noted after clicking the
' "Display Image" button. Therefore a comparison can be made between Value property and ChunkSize
' property and an optimized ChunkSize value can be found for retrieving images.
'
'***************************************************************************************
 
Option Explicit

'a single session of connection used throughout the form
Dim m_Oracon As ADODB.Connection

'recordset for populating product_id and product_name in the combobox
Dim m_recProductInformation As New ADODB.Recordset

'variable for holding ChunkSize value entered in the textbox
Dim m_chunksize As Long

'"QueryPerformanceCounter" is used to obtain the current reading of the system's
'high-performance timer. The high-performance timer is a counter that the system
'increments many times a second.
Private Declare Function QueryPerformanceCounter Lib "Kernel32" _
                                         (X As Currency) As Boolean
                                         
'"QueryPerformanceFrequency" obtains the frequency of the
'high-performance timer to measure small intervals of time precisely.
Private Declare Function QueryPerformanceFrequency Lib "Kernel32" _
                                         (X As Currency) As Boolean


'**************************************************************
' This sub procedure populates the  select product combobox
' with products from Product_Information database table.
'**************************************************************

Private Sub Form_Load()

Dim i As Integer 'counter variable
i = 0
 
 
On Error GoTo ErrorText 'redirect to error handler
 
 
'setting mouser pointer on "frmChunkSize" form to wait state
frmChunkSize.MousePointer = vbHourglass
 
 
'set connection parameters in connectionParams.bas module
connectionParams.setparams
 
Set m_Oracon = CreateObject("ADODB.Connection") 'creates a connection object
 
'setting information for establishing connection
'set provider and connection parameters for database connection
m_Oracon.Provider = "OraOLEDB.Oracle"
 
'get the connection parameters from "connectionParams.bas" file
m_Oracon.ConnectionString = "Data Source=" + connectionParams.datasource & _