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Birgitta Hauser wrote:
There is a nice article about the differences between DDS described physical
and logical files and SQL Defined Tables, Views and Indexes:
Modernizing Database Access
The Madness Behind the Methods
By Dan Cruikshank
http://www-03.ibm.com/systems/resources/systems_i_software_db2_pdf_Performance_DDS_SQL.pdf
That's a nice link Birgitta, thank you. Somehow I missed it when it
came out in January 2006. I'm sure it must seem to you that you repeat
yourself endlessly, but those repetitions can always help a new person...
I was a bit doubtful that an SQL table always validated on the write, so
I did a small experiment.
CREATE TABLE buck/ddl (nbr DECIMAL(9,0) NOT NULL DEFAULT 0,txt
char(50) not null )
ovrdbf dds ddl
call ddsddl
Data mapping error on member DDL.
C
I/O error CPF5029 was detected in file DDS.
Application error. RNX1299 unmonitored by DDSDDL at statement
0000000015, instruction X'0000'.
The RPG program is simple too:
* test data validation for DDS files vs DDL files
fdds uf a f 55 disk
idds aa 01
i 1 5 nbr
i 6 55 txt
c eval nbr = '$bad$'
c eval txt = '$bad$'
c except writedds
c eval *inlr = *on
odds eadd writedds
o nbr 5
o txt 55
For completeness, I also ran the program over a DDS-defined file:
A R DDSR
A NBR 9P 0
A TXT 50A
and it runs without error.
Very much something to think about.
Viel danke.
--buck
midrange.com
