Q171668: FIX: Shared Table in DBC Remains Locked After Table Update

Article: Q171668
Product(s): Microsoft FoxPro
Version(s): WINDOWS:5.0,5.0a
Operating System(s): 
Keyword(s): kbvfp kbvfp600fix
Last Modified: 24-MAR-2000

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a 
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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

Additional query words:

======================================================================
Keywords          : kbvfp kbvfp600fix 
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP500a
Version           : WINDOWS:5.0,5.0a
Issue type        : kbbug kbprb
Solution Type     : kbfix

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