Let's say I'd like to keep 5 data items as "permanent" accross program restarts. They change frequently. For example counters that are used as keys for next table records.
Is keeping these counters in a memory mapped file, recommended? The nature of the counters is that they just need to never be reused, so they are incremented when read, and it is no big deal if there is a perfectly timed power outtage that doesn't cause the counter to be incremented, because that power outtage would also prevent the retrieved value from being used. It would also not be a major problem (though still not desirable) if the file became corrupted, because there is a procedure that can find the last counter (though it is more expensive than typical database apps of looking at the last record). What would be a major problem is if there is a lazyness to the writing of memory mapped files such that the retrieved counter value can be used without any guarantee that the file will be updated... that is if a power failure could occur 1 second or so after the memory mapped variable is updated, but the file would not be. If using memory mapped files this way is recommendable, is it best to used separate files for each (handful of) variable or a single file? ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
