Microsoft KB Archive/199005

= ACC2000: Manipulating Objects with ADO May Cause Database Bloat =

Article ID: 199005

Article Last Modified on 6/23/2005

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APPLIES TO


 * Microsoft Access 2000 Standard Edition

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This article was previously published under Q199005



Advanced: Requires expert coding, interoperability, and multiuser skills.



SYMPTOMS
When you use ActiveX Data Objects (ADO) to create objects in a database, the size of the database increases substantially during the operation. After compacting, the size of the database is much smaller.



RESOLUTION
Use SQL Data-Definition Language (DDL) statements rather than ADO to create or modify database objects. For example, you can use the following procedure to work around the behavior demonstrated in the "Steps to Reproduce Problem" section later in this article:

Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements. Sub CreateTables

Dim ADOCon As New ADODB.Connection Dim ADOCmd As New ADODB.Command Dim MyStr As String Dim i As Integer, j As Integer

' Use active Access connection. Set ADOCon = CurrentProject.Connection

For i = 1 To 20 ADOCon.Execute "CREATE TABLE tblTest" & i     For j = 1 To 200

ADOCon.Execute "ALTER TABLE tblTest" _ & i & " ADD Field" & j & " Text"

Next Next Application.RefreshDatabaseWindow

End Sub



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.



MORE INFORMATION
This behavior typically occurs when you use ADO to create or modify a large number of database objects. The following example demonstrates this by using ADO to create twenty tables, each with two hundred fields. In this example, reducing the number of fields created in the example greatly reduces the amount of database bloat.

NOTE: The sample code in this article uses Microsoft ActiveX Data Objects. For this code to run properly, you must reference the Microsoft ActiveX Data Objects 2.x Library (where 2.x is 2.1 or later.) To do so, click References on the Tools menu in the Visual Basic Editor, and make sure that the Microsoft ActiveX Data Objects 2.x Library check box is selected.

The sample code in this article uses ADO Extensions for DDL and Security. For this code to run properly, you need to reference the Microsoft ADO Ext. 2.1 for DDL and Security.

Steps to Reproduce Problem
 Open the sample database Northwind.mdb. On the Tools menu, point to Database Utilities, and then click Compact and Repair Database. Press CTRL+G to open the Immediate window.  Type the following in the Immediate window, and then press ENTER: ?FileLen(CurrentDb.Name) Note that this function returns the file size in bytes of the currently opened database (Northwind.mdb). Take note of the current size.   Create a module and type the following line in the Declarations section if it is not already there: Option Explicit </li>  Type the following procedure: Sub ADOX_CreateTables

Dim cat As New ADOX.Catalog Dim conn As New ADODB.Connection Dim tbl As New ADOX.Table Dim i As Integer, j As Integer

Set conn = CurrentProject.Connection Set cat.ActiveConnection = conn

For i = 1 To 20

With tbl 'Create a new table .Name = "tblTest" & i

'Add 200 text fields For j = 1 To 200 .Columns.Append "Field" & j, adVarWChar, 50 Next j     End With

'Append the table into the Catalog's tables collection cat.Tables.Append tbl Set tbl = Nothing

Next Application.RefreshDatabaseWindow

End Sub </li> On the File menu, click Save Northwind. When Microsoft Access prompts you to save the module, click Yes. In the Save As dialog box, click OK to accept the default name.</li>  To run this procedure, type the following line in the Immediate window,and then press ENTER. It may take several minutes for this procedure to run. ADOX_CreateTables Note that twenty tables are added to the database, each with two hundred fields. </li>  Type the following line in the Immediate window, and then press ENTER: ?FileLen(CurrentDb.Name) Note that the size of the Northwind.mdb file is now is significantly greater. </li> On the taskbar click Microsoft Access (or Northwind: Database) to get back to the Database window.</li> On the Tools menu, point to Database Utilities, and then click Compact and Repair Database.</li> Press CTRL+G to open the Immediate window.</li>  Type the following in the Immediate window, and then press ENTER: ?FileLen(CurrentDb.Name) Note that the size of the Northwind.mdb file after compacting is now closer to the size that you saw on step 4. </li></ol>

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