Re: Use of Triggers in RPG

Paul,
 
You should figure out what you want to do if there is a problem in the trigger 
(for instance, if the stats file is locked by another job or whatever). Do you 
want to stop the write to the transaction file, or go ahead with it anyway? 
Ensure you build full error-handling into your trigger program and code 
defensively... Very defensively.
 
If you're worried about a performance hit (as Todd mentions) you could consider 
writing a trigger program which puts the transaction details (or whatever it is 
you want to log into your stats file) onto a data queue and then returns 
control to the database manager, rather than actually writing to the stats file 
itself. That way, the trigger program runs very quickly, and the data queue 
receiver program (which you will also have to write) can be the one which 
actually writes the record into the stats file. It's a more complex solution, 
but you're less likely to hit performance issues. However, you can't use this 
type of processing to stop a transaction from occurring, if that's what you 
want to do.
 
Check on posts from Alan Campin (either in this forum or in the MIDRANGE-L 
forum) from the last couple of months - he wrote a generic 'trigger mediator' 
which may include data queue functionality. I wrote one a year ago, but it's my 
company's property, so I can't share it. Either way, Alan's stuff may be a good 
start on what you want to acheive if you haven't worked with trigger programs 
before.
 
HTH,
 
Rory