RE: EXEC SQL vs. CHAIN performance considerations

Brian,

Using SQL for single record access is typically slower than using the
native methods due to additional overhead. If you are getting a large
number of records, SQL may be faster (particularly if you fetch multiple
records at the same time). 

The one exception that I'm aware of where single record SQL is faster
than the native methods is remote access to another machine. To use the
native methods on a remote machine, you need to use DDM files. DDM files
are not exactly the best performing things (error recovery is pretty
much non-existent as well but that doesn't have anything to do with
performance).

The best way to find out if there's going to be a performance hit is to
write the program both ways and see which is faster.

Matt

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Brian Piotrowski
Sent: Monday, June 06, 2005 8:01 AM
To: RPG programming on the AS400 / iSeries
Subject: EXEC SQL vs. CHAIN performance considerations

Hi All,

 

I have a rather complex SQL statement that I have been using the in the
SQL interpreter to retrieve data from a physical file.  I am toying with
the idea of implementing this code into my RPG program instead of
writing code using chain, setll, etc. to accomplish the same thing.

 

Can I expect a significant performance hit in using this method of data
manipulation instead of using the native commands to access data on the
physical file?

 

Thanks!


Brian.

 

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Brian Piotrowski

Specialist - I.T.

Simcoe Parts Service, Inc.

Ph: 705-435-7814 x343

Fx: 705-435-6746

bpiotrowski@xxxxxxxxxxxxxxx

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