RE: Triggers or Journals?

[Evan Harris <spanner@xxxxxxxxxx>]

NSmith wrote:

>Journals just monitor what is going on, whereas triggers can be written to
>be an active part of the process.

Agreed. But the original question was about audit trails and IMHO it is 
almost impossible to beat a journal for audit trail purposes. The trigger 
has to be added to all the files and maintained, if it does something extra 
you need to make sure the audit trail is not compromised etc etc. Once the 
file is journalled you have the audit trail no ifs, buts or maybes.  A 
journal will also take care of anything a trigger does to a file without 
any thinking on the programmers part so a trigger in one file that updates 
another will produce an audit trail for that file if it is journalled 
without any additional thought.

>For example, if you require only uppercase data in a field, and someone
>enters lowercase, the trigger could convert it before letting the record
>pass.  Or, it could default values into a field when it doesn't like what is
>being written.  Or, if you are using Ref. Constriants, and a record is
>written which violates that constraint, the program will get a "hard" crash.
>A trigger could test for the same rules and stop the update and send an
>error message to the program which could handle the error a little more
>elegantly.  Triggers are also great for "housekeeping" chores, like
>timestamping, assigning the next sequential key, etc.

Agreed, but IMHO opinion it is better to separate these chores from the 
chore of producing an accurate audit trail every time. Also, in those 
instances where you ONLY need the audit trail why add a trigger and the 
extra maintenance that implies when you can just use a journal ? The two 
functions are quite separate in my mind.

>If written properly, the same program being used as a trigger can be called
>by a program directly to perform the field editing functions before writing
>the actual record,  thereby giving the maintenance program a "heads-up" on
>what the trigger is going to find and consolidating all editing in one place
>for consistency.

Agreed, this is the kind of thing that triggers excel at.

>As far as uses for audit files, I've found them invaluable in researching
>problems and for reconstructing point-in-time statuses.

Just my take on things

Cheers
Evan Harris

> > -----Original Message-----
> > From: Chris Bipes [SMTP:chris.bipes@cross-check.com]
> > Sent: Wednesday, March 28, 2001 11:28 PM
> > To:   'midrange-l@midrange.com'
> > Subject:      RE: Triggers or Journals?
> >
> >
> > Does any one else have any thing else to add?
> >
> > Christopher K. Bipes  mailto:ChrisB@Cross-Check.com
> > Sr. Programmer/Analyst        mailto:Chris_Bipes@Yahoo.com
> > CrossCheck, Inc.      http://www.cross-check.com
> > 6119 State Farm Drive Phone: 707 586-0551 x 1102
> > Rohnert Park CA  94928        Fax: 707 586-1884
> >
> >
> >
> >
>
>
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