How to prevent database bloat after you use Data Access Objects (DAO)

Moderate: Requires basic macro, coding, and interoperability skills.

This article applies only to a Microsoft Access database (.mdb).


For a Microsoft Access 2000 version of this article, see
209847 .
For a Microsoft Access 97 version of this article, see
186311 .

Symptoms

A Microsoft Access database has begun to bloat (or grow rapidly in size) after you implement Data Access Objects (DAO) to open a recordset.

Cause

If you do not release a recordset's memory each time that you loop through the recordset code, DAO may recompile, using more memory and increasing the size of the database.

Resolution

To avoid consuming unnecessary resources and increasing database size, use the Close method of the Recordset object to explicitly close the recordset's memory when you no longer need the recordset.

If the database has increased in size because you did not use the Close method of the Recordset object, you can reduce the size of the database by running the
Compact and Repair utility (on the Tools menu).

More Information

When you create a Recordset (or a QueryDef) object in code, explicitly close the object when you are finished. Microsoft Access automatically closes Recordset and QueryDef objects under most circumstances. However, if you explicitly close the object in your code, you can avoid occasional instances when the object remains open. The following steps show you how to use DAO to close a Recordset or QueryDef object.
  1. Start Microsoft Access.
  2. Open the sample database Northwind.mdb.

    NOTE: The sample code in this article uses Microsoft Data Access Objects. For this code to run properly, you must reference the Microsoft DAO 3.6 Object Library. To do so, click References on the Tools menu in the Visual Basic Editor, and make sure that the Microsoft DAO 3.6 Object Library check box is selected.

  3. Copy the following code to a new module. The following sample code opens and closes a Recordset and a QueryDef object, and displays both Recordset and QueryDef information within message boxes.
    Option Compare Database
    Option Explicit

    Sub subCloseObjects()
    Dim db As DAO.Database
    Dim rs As DAO.Recordset
    Dim qd As DAO.QueryDef

    Set db = CurrentDb
    Set rs = db.OpenRecordset("Employees", dbOpenTable)
    Set qd = db.QueryDefs("Invoices")

    rs.MoveLast 'Move to the last record in the Recordset.

    MsgBox "The Employees Recordset is open." & vbCrLf & _
    "The last Employee ID is " & rs![EmployeeID] & "."
    MsgBox "The Invoices query definition is open." & vbCrLf & _
    "The first field in the query is " & qd.Fields(0).Name

    'Explicitly close the Recordset and QueryDef objects.
    rs.Close
    qd.Close
    End Sub
  4. Run the subCloseObjects routine.
Właściwości

Identyfikator artykułu: 289562 — ostatni przegląd: 30.10.2008 — zmiana: 1

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