|
You are right, SQL checks during Writes, RPG native I/O checks during reads.
I like to refer people to this nice Dan Cruikshank paper: "Modernizing
Database Access The Madness Behind the Methods ",. You can find it at:
http://www-03.ibm.com/systems/resources/systems_i_software_db2_pdf_Performance_DDS_SQL.pdf
HTH,
Luis Rodriguez
IBM Certified Systems Expert - eServer i5 iSeries
On Fri, Jun 4, 2010 at 3:31 PM, Bryce Martin <BMartin@xxxxxxxxxxxx> wrote:
I'm not sure what SETOBJACC is or what effect it has on reading a file...--
but....
Doesn't RPGLE do its checks on Read as opposed to SQL that does checks on
Write? So as I've heard it the general idea goes that reading with SQL
should be faster than RPGLE but writing would be the other way around. So
why not write and SQL to read the data and only the fields you need (which
is proven to be faster than specifying SELECT * FROM)? You can fetch more
than one row at a time I do believe and I think would perform better than
a single record by record read using native I/O.
Then again, if I have the idea of when the i/o checks happen respective to
read vs. write then everything I said above is for naught!
Thanks
Bryce Martin
Programmer/Analyst I
570-546-4777
Kurt Anderson <kurt.anderson@xxxxxxxxxxxxxx>
Sent by: rpg400-l-bounces@xxxxxxxxxxxx
06/04/2010 02:12 PM
Please respond to
RPG programming on the IBM i / System i <rpg400-l@xxxxxxxxxxxx>
To
"'RPG programming on the IBM i / System i'" <rpg400-l@xxxxxxxxxxxx>
cc
Subject
Speed in Reading
Hi all,
Lately I've been dealing with a new client that has a high volume of data
for us to process, so I've been looking at various ways to get things
moving a little faster.
I believe I've successfully implemented the use of SETOBJACC with the help
of Chuck Pence & Mark Waterbury (thanks guys).
Now, this may be grasping at straws, but in a high data volume situation,
should I see any benefit in restricting the fields in a LF to only the
fields used by the program? (In essence, going from record length of 438
to 138.) My brain says, "yes," but the logic under-the-covers may not
match the logic my brain uses to come to its conclusion.
I'm also curious about RPG blocking. This question mainly goes out to
people using file encapsulation service programs, but is obviously open to
anyone to answer. I have a file wrapped up in a service program. This
service program pretty much handles all I/O operations for the file. Now,
if all I want to do is loop through the file, it's not going to block read
because it has operations such as READE in the service program. I wish
block-reading would be determined at run-time (again, a wish without a
full understanding of the compiler does its thing). I'm curious how
people have circumvented this limitation?
Thanks,
Kurt Anderson
Sr. Programmer/Analyst
CustomCall Data Systems
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