C5_SET EXCLUSIVE

SET EXCLUSIVE*
 Establish shared or exclusive USE of database files
------------------------------------------------------------------------------
 Syntax

     SET EXCLUSIVE ON | off | <xlToggle>

 Arguments

     ON causes database files to be opened in exclusive (nonshared) mode.

     OFF causes database files to be opened in shared mode.

     <xlToggle> is a logical expression that must be enclosed in
     parentheses.  A value of true (.T.) is the same as ON, and a value of
     false (.F.) is the same as OFF.

 Description

     In a network environment, SET EXCLUSIVE determines whether a USE command
     specified without the EXCLUSIVE or SHARED clause automatically opens
     database, memo, and index files EXCLUSIVE.  When database files are
     opened EXCLUSIVE, other users cannot USE them until they are CLOSEd.  In
     this mode, file and record locks are unnecessary.

     When EXCLUSIVE is ON (the default), all database and associated files
     open in a nonshared (exclusive) mode unless the USE command is specified
     with the SHARED clause.  Use EXCLUSIVE only for operations that
     absolutely require EXCLUSIVE USE of a database file, such as PACK,
     REINDEX, and ZAP.

     When EXCLUSIVE is OFF, all files are open in shared mode unless the USE
     command is specified with the EXCLUSIVE clause.  Control access by other
     users programmatically using RLOCK() and FLOCK().

     SET EXCLUSIVE is a compatibility command and not recommended.  It is
     superseded by the EXCLUSIVE and SHARED clauses of the USE command.

     Refer to the "Network Programming" chapter in the Programming and
     Utilities Guide for more information.

 Notes

     .  Error handling: Attempting to USE a database file already
        opened EXCLUSIVE by another user generates a runtime error and sets
        NETERR() to true (.T.).  After control returns to the point of error,
        you can test NETERR() to determine whether the USE failed.

 Files   Library is CLIPPER.LIB.

See Also: FLOCK() NETERR() RLOCK() USE

 

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2 responses to “C5_SET EXCLUSIVE

  1. Pingback: DB Commands | Viva Clipper !

  2. Pingback: C5 Commands | Viva Clipper !

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