| When the
'+F' parameter is enabled the system will defer the
actually physical close of data files and can re-use
these logically closed files later in the program if they
are re-opened. In effect it 'caches' file connections. In most operating enviromnents
there is a lot of system overhead in the opening and
closing of data files. Using the '+F' parameter can
improve throughput if the application constantly opens
and closes the same file over and over again. Consider
for example a subroutine that opens a file to look up a
piece of information then closes this data file once it
has the information it needs and returns to the called.
This routine would open/close the same file each and
every call which could slow down the system. Setting the
'+F' parameter avoids the operating system overhead
involved with the open/close.
The system attempts to
determine which files can have there connection cached to
avoid problems within your application. The following
rules are applied:
- The file must be
KEYED (VLR or EFF), INDEXED or SERIAL
- The file must be
opened for full Read/Write access
- The file can not have
been LOCKed by the application.
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