RE: CLOB vs STRING

["Christen, Duane" <Duane.Christen@xxxxxxxxxx>]

David,

I use CLOBS in several DBs, to store XMLs, pictures, engineering drawings... I also use Data Links (to IFS files)

When I build the DB I put the CLOB/DL in a child table, referentially constrained to the parent, so only when I need to access the CLOB/DL do I even open the table.

I've never done any performance testing, we haven't had any complaints :), so I don't know what the difference between CLOBs, DLs, and using some other method(s).

I prefer CLOBs, but I use DLs when the data "more easily" exists in the IFS, and I need to guarantee it exists as long as the DB record(s). 

Duane Christen

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Scott Klement
Sent: Wednesday, February 16, 2011 3:51 PM
To: RPG programming on the IBM i / System i
Subject: Re: CLOB vs STRING

Hi David,

CLOB cannot be used with RLA.  It may not work as expected with various 
tools (CPYTOSTMF, CPYTOIMPF, et al), and I have no clue what happens if 
you try to FTP a file with a LOB in it.

CLOB variables are never stored in the record buffer, they have to be 
fetched separately, which performs slower.  (You can make CHAR/VARCHAR 
work that way as well, but it's not that way by default.)

On the other hand, LOB variables (CLOB, BLOB, DBCLOB) have the advantage 
that they can be very large (megabytes).  That's simply not possible 
with CHAR/VARCHAR.

So they are good for some things, and bad for others.  It's just a 
matter of using the right tool for the job.


On 2/16/2011 2:25 PM, dmosley@xxxxxxxxxx wrote:
> Does anyone know of any problems (performance-wise, or something else)
> when using a CLOB RPG variable.
>
> We have stored procedures that  calls normal RPG programs.  We had a very
> generic parameter set where one of the IN params was a 32,000 VARYING
> field.
> Well, the value of the field got to be too large so we changed it to a
> (CLOB:64,000).  Now, we are thinking of rasing that size up as well.
>
> So, I'm just curious to know if anyone has used them much, and if , (in
> there own opinion), are a good idea or not.  And why.
>
> Thanks everyone,
> David
>
>
> David L. Mosley, Jr.
> Technical Solutions Architect
> Dancik International, Ltd.
> 2000 CentreGreen Way, Suite 250
> Cary, NC 27513
>
> www.dancik.com