FIX: Shared Table in DBC Remains Locked After Table Update (171668)


The information in this article applies to:

  • Microsoft Visual FoxPro for Windows 5.0
  • Microsoft Visual FoxPro for Windows 5.0a
This article was previously published under Q171668

SYMPTOMS

When using optimistic table buffering on a table inside a database container (DBC), a shared table remains locked after a table update that occurs within a transaction. This situation prevents other users from updating the table. The behavior occurs when the table is in a DBC, the table update is within a transaction and the buffer mode is optimistic table. The behavior does not happen when the table is free.

RESOLUTION

One resolution is to use free tables instead of tables within a database.

Another option is to check, within the transaction, whether the table is locked (ISFLOCKED() returns True) and if the table is locked, use the UNLOCK command to unlock the table.

A third resolution to perform a REPLACE on more than one record is to put the REPLACE statement within a loop so that the scope of the REPLACE statement affects only a single record.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This has been corrected in Visual FoxPro 6.0.

MORE INFORMATION

NOTE: This problem occurs only when the scope of records affected by the REPLACE function is more than one.

Steps to Reproduce Behavior

The following code will demonstrate the behavior: 
   * Start of the Code
     CLEAR
     CLOSE DATABASES ALL
     SET MULTILOCKS ON
     SET SAFETY OFF
     SET TALK OFF

   * Create the database and table

   *********************************************************************
   * NOTE: If the table is not in a database the problem does not occur.
   *       The following line can be removed to verify this behavior.
   *********************************************************************
     CREATE DATABASE test

     CREATE TABLE test (CTest C(10) , NTest I)

     INSERT INTO Test VALUES ( "one", 1)
     INSERT INTO Test VALUES ( "two", 2)
     INSERT INTO Test VALUES ( "three", 3)
     INSERT INTO Test VALUES ( "four", 4)

     CLOSE DATABASES ALL

     USE Test SHARED
     =CURSORSETPROP( "buffering", 5) && Optimistic Table Buffering

     REPLACE NEXT 2 cTest WITH "test"

     BEGIN TRAN
        IF NOT TABLEUPDATE( 2, .F., "Test")
           ? "Failed."
        ELSE
           ? "Committed."
        ENDIF
     END TRAN

     IF ISFLOCKED( "Test")
      * UNLOCK in test && Uncomment this line to test the UNLOCK command
        ? "The table is still locked."
     ELSE
        ? "The table is not locked."
     ENDIF
     ?ISFLOCKED()
   * End of the Code
Modification Type:MajorLast Reviewed:3/24/2000
Keywords:kbbug kbprb kbvfp600fix KB171668
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