Re: Perform trigger upon read

Since it looks like read-triggers may arrive in v5r1, I have to wonder about 
both the potential performance impacts and the technical difficulty in 
implementing them in DB2/400.

For example, I suspect there may be a lot of program changes coming up where 
past programmers have used CHAINs rather than SETLL to test for simple 
existence. And anywhere a CPYF or similar (CRTDUPOBJ DATA(*YES), CPYTOIMPF, 
CPY, FTP, ODBC, you name it) might be involved would have to be considered 
before setting a read-trigger. And RPG READs prior to UPDATE or DELETE where 
triggers are already set? And how would that relate to an SQL UPDATE? 
Interesting times, potentially.

As for simply getting them into DB2/400, I can barely imagine some of the 
decisions that had to be made since I'm not well versed in the layers of 
database management. Under what circumstances should the trigger fire? If I 
cause a full table scan via a SELECT ORBER BY, I probably don't want want it to 
fire; so there will be a layer where the trigger is inactive or a way to turn 
it off. Various other possibilities exist. Going to be fun trying to find the 
boundaries.

I wonder how many DB2 group PTFs are coming up.

Tom Liotta

On Wed, 28 March 2001, shahar mor wrote:

> 
> Hi all,
> 
> I know this is a weird question but i'll ask anyhow:
> 
> The as400 does not support triggering of read
> operations. 
> 
> I need to log requests to several files in medical
> application and i do not have the ability to update
> the application source.
> 
> So, i'm looking for a bright way to log read requeest
> made to file outside the application (the read is
> performed from rpg).
> 
> Thanks in advance for any input on this subject
> 
> 
> =====
> Shahar mor
> consultant

-- 

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