KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q176483: PRB: Large Amounts of RAM Seem to Process Data Slowly

Article: Q176483
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0,3.0b,5.0,5.0a,6.0
Operating System(s): 
Keyword(s): kbvfp kbvfp300 kbvfp300b kbvfp500 kbvfp500a kbvfp600
Last Modified: 06-AUG-1999

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a, 6.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

Sometimes when you manipulate a table with certain FoxPro commands, the record
counter on the status bar pauses or stops for long periods of time. The hard
drive continues to process information. This problem is more noticeable on
faster computers that have large amounts of RAM installed.

RESOLUTION
==========

Set the foreground buffer of SYS(3050) to a smaller number. Here's an example:

       =SYS(3050,1,10000000) && Sets the foreground buffer to 10 million
                             && bytes.

STATUS
======

This behavior is by design.

MORE INFORMATION
================

Using the commands COPY, APPEND, DELETE, INDEX, PACK or SQL-SELECT on a large
table in Visual FoxPro causes long pauses while the data is being manipulated.
The hard drive continues processing the data, but Visual FoxPro seems to be
inactive. This happens because computers that have large amounts of RAM and are
running Windows 95 or Windows NT give Visual FoxPro a large amount of buffered
memory to use. This memory is composed of RAM and physical hard drive space.
When FoxPro writes data into memory, large temporary files are created. When
they are written to the virtual memory (the hard drive), that memory is always
slower. Using a smaller amount of foreground buffer memory with SYS(3050) makes
Visual FoxPro use only the RAM memory, which is faster. Reducing the foreground
buffer size has eliminated the long delay in most situations.

Steps to Reproduce Behavior
---------------------------

1. Use a computer with 64 MG of RAM or more, Visual FoxPro, and a table that
  contains 2 million or more records.

2. Open the table, issue a SET STATUS BAR ON, and a COPY TO test in the FoxPro
  Command window.

3. Watch the record counter on the status bar as it starts counting the copied
  records. After a while, the counter stops but the hard drive continues to
  process data. Later, the record counter starts counting again and then pauses
  after doubling the last record count.

4. Press the ESC key after watching this behavior, and type the following in the
  FoxPro Command window:

  

          =SYS(3050,1,10000000)  && The 10 million number can be changed to
                                 && suit individual situations.

5. Issue a COPY TO test command again and note that the counter does not pause
  as long this time.

REFERENCES
==========

Visual FoxPro Help File: SYS(3050)

"Foxtalk," February 1997, "Set Turbo On: How Visual FoxPro Memory Usage Affects
Performance," page 1, Flavio Almeida and Walter Loughney

Additional query words: slow freeze VFoxWin

======================================================================
Keywords          : kbvfp kbvfp300 kbvfp300b kbvfp500 kbvfp500a kbvfp600 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP300b kbVFP500 kbVFP600 kbVFP500a
Version           : WINDOWS:3.0,3.0b,5.0,5.0a,6.0
Issue type        : kbprb

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.