READ NOLOCK Behavior in Visual FoxPro (131031)

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READ NOLOCK alters the behavior of the READ command, so records are not automatically locked by the READ.

In FoxPro version 2.x, issuing a READ NOLOCK command automatically disables all fields. Attempts to key data into the fields causes a high-pitched beep until a SHOW GETS LOCK command is issued.

In Visual FoxPro, the beep is no longer heard. Instead, a "Record is read only" message appears on the status bar. A SHOW GETS LOCK command is still required to edit the fields.

If buffering is enabled, the READ NOLOCK command overrides the locking behavior of the buffering mode that is in effect. If pessimistic locking is enabled, the record is not locked until the SHOW GETS LOCK command is issued. If optimistic locking is enabled, the record is locked at the time the SHOW GETS LOCK is issued, not at the time the record is written to disk.

The TABLEUPDATE() and TABLEREVERT() commands should not be used in conjunction with READ NOLOCK. You should modify the application to use buffering completely or to use READ NOLOCK without enabling buffering.