Optimizing Visual FoxPro in a Multiuser Environment

When you run Visual FoxPro or Visual FoxPro applications in a multiuser environment, you can improve performance by managing storage of temporary files and controlling the way tables are shared.

Managing Temporary Files

In most multiuser environments, it is recommended that you save temporary files to local disks or memory when networked computers contain large amounts of free disk space. Redirecting storage of temporary files can improve performance by reducing frequent access to the network drive.

On small networks with older networked computers and slow hard disks, you might experience better performance by leaving Visual FoxPro temporary files on the file server; however, when in doubt, direct temporary files to the local disk. When working on large, heavily used networks, always redirect temporary files to the local disk.

By saving all temporary files to a single directory on a local hard drive, you can safely erase the contents of the temporary file directory on the file server prior to each Visual FoxPro session. This action purges the system of any temporary files that were created but not erased by Visual FoxPro due to a system reboot or power loss.

For more information about temporary files, see Optimizing the Operating Environment and How to: Specify the Location of Temporary Files.

Sharing Tables

If users share tables on a network, the way you manage access to them can affect performance.

  • Avoid opening and closing tables repeatedly.

  • Buffer write operations to tables that are not shared.

  • Provide exclusive access to tables.

  • Limit the time on locking tables.

Providing Exclusive Access

You can enhance performance for the APPEND, REPLACE, and DELETE commands and operations that run at times when no other users require access to the data, for example, overnight updates, by opening data files for exclusive use. When tables are open for exclusive use, performance improves because Visual FoxPro does not need to test the status of record or file locks.

To open data files for exclusive use, use the EXCLUSIVE clause in the USE and OPEN DATABASE commands. For more information, see USE Command and OPEN DATABASE Command.

Limiting the Time on Locking Tables

You can reduce contention between users for write access to a table or record by shortening the amount of time for locking a record or table. Instead of locking a record while the user edits it, lock the record only after it has been edited. Using optimistic row buffering provides the shortest amount of time that records are locked. For more information, see Buffering Data.

See Also

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