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Data validation code is the part of the database code that checks whether data is valid - you know, like decimal data errors. According to what is said below, the extra overhead is added on reads in DDS-based files (non-SQL), on the writes on DDL-based files (SQL). If, in fact, your apps do more reads than writes, it could be somewhat advantageous to change to SQL-built tables. But I think the jury is still out, and you should use DSPFD on the various files to see what the actual behavior has been historically - it's all in there. Remember, updates are a combination of a read and a write, basically, so add that to both the number of reads and the number of writes, I think.

All this talk of converting to SQL-based tables does not take into account the issues around the journals associated with SQL collections (read that to mean a library, the various SYS* views in said library, and attendant journals and journal receivers). If you need to copy them to a different location, it is not pretty. There have been several posts here about this, and Kent Milligan has a white paper on this - I forget the link, try digging around at www.iseries.ibm.com/db2 - I find that SQL Server has some really nice stuff in its RESTORE DATABASE... functionality, but then it doesn't use journals, AFAIK, for transaction processing (commitment control to us iSeries folks).

I think we need something from IBM to handle this better. Maybe a way to put new library references into the journal receivers, and into the SYS* views - I don't know. They're smart folks and ought to be able to find a way for moving/copying a collection not to be so hard. I mean, they wrote CHGPF over a source member, right?

Whew!!!
Vern

At 01:11 PM 9/8/2005, you wrote:

Is there anyone who can explain this? Data Validation code!  Or point to
the original article?

Thanks
-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of DeLong, Eric
Sent: Wednesday, September 07, 2005 4:22 PM
To: 'Midrange Systems Technical Discussion'
Subject: RE: SFL Load - SQL vs. LF

IBM has changed the data management rules for files created via DDL,
which
effective improves DB thruput for all applications using the file.
Performance gains come from where IBM has chosen to implement the data
validation code.  Under DDS rules, data is validated when it is read
from
the disk, where DDL moves the validation to DB writes and updates.

The theory is that a typical application will read data much more than
it
writes data.  If we validate on write, then we've reduced IO overhead.

iSeriesNetwork had an article about this.....

Eric DeLong
Sally Beauty Company
MIS-Project Manager (BSG)
940-297-2863 or ext. 1863



-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx]On Behalf Of James H H Lampert
Sent: Wednesday, September 07, 2005 1:09 PM
To: Midrange Systems Technical Discussion
Subject: Re: SFL Load - SQL vs. LF


Billy Rowe <billyrowe@xxxxxxx> wrote:
> No matter which presentation method you decide to you,
> definitely create the tables/indexes/views with SQL.

Why?

--
JHHL
(who is much more fluent in DDS and OPNQRYF than with SQL)
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