RE: SFL Load - SQL vs. LF

[Vernon Hamberg <vhamberg@xxxxxxxxxxx>]

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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