March Products 204 - Manual (Page 17)

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The Refresh Process
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CHAPTER 3
The Refresh Process
The Refresh process checks file tables and updates the SirFile database. You can
request a refresh operation to run once or periodically.
1. Running a refresh once always runs in the Model 204 thread of the user requesting
the refresh, and can be specified either for a single file or for all files that SirFile can
access. This can be invoked via:
● the Main File menu, using either the ADD or REFRESH command or using
PF12
● any of the File Tables, System Default thresholds, or File thresholds screens,
using
PF12
● the SIRFILE BATCH command. The SIRFILE BATCH command is usually
invoked only in a BATCH204 jobstream, to be run when files are not open for
update by any online. See “Running SirFile under BATCH204” on page 35 .
2. A periodic refresh, which repeats at a specified time interval, is also called the
Background Monitor. This can be invoked via:
● the Background Monitor specification screen, using
PF5 . This runs the refresh
on an sdaemon thread, that is, a different thread from the requesting user.
● the SIRFILE BACKGROUND interval command. This runs the refresh on an
sdaemon thread, that is, a different thread from the requesting user, and it may
be useful in the online's User 0 stream.
● the SIRFILE SDAEMON interval command. This runs the refresh on the
thread of the requesting user, and it is most often invoked by a BATCH2 or
IODEV=3 thread.
“Invocation Techniques for Background Monitoring” on page 33 and “Running
SirFile under BATCH204” on page 35 further discuss considerations of periodic
refreshes.
Whenever the refresh operation is performed, it can consume considerable resources if
it calculates the CFULLP (Table C percentage full) value. One of the values specified on
the System Default thresholds screen is whether to allow file-by-file determination of
CFULLP calculation. If file-by-file CFULLP determination is allowed, then CFULLP is
calculated during any type of refresh, for exactly those files which are specified as
having CFULLP calculation performed. If CFULLP calculation is not determined on a
file-by-file basis, then CFULLP calculation is performed for all files by the SIRFILE
BATCH command, and is not performed by any other type of refresh.
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SirFile User's Guide 11