DDS vs DDL

[kitvb1]

I'm trying to use DDL, as opposed to DDS, to create a new interface to our logistics company. Got the source and objects for the files they will be transmitting to us.

While using OPS Nav to Generate SQL for the tables and indexes, I notice that all existing LF's are regarded as views and not indexes.

from IBM Redbook sg24-6393-00.pdf:

[U]SQL term        iSeries term[/U]
Table            Physical file
View             Non keyed logical file
Index            Keyed logical file

Any ideas as to why this is?

TIA

[tomholden]

Re: DDS vs DDL

personally i think that is one of the most idiotic things about how IBM treats DDL. it always treats DDS LFs as views. the more appropriate behavior would have been to treated LFs that only change key values as indexes and select/omits as unkeyed views. but i digress....the mentality (or reason) is that DDS LFs are all select/omit by default they are created as SELECT ALL logical views (hence their line of thought). but with SQL an index is not a select all view..it's truly an index (access path...i'm sure Birgitta can explain this much better than i can) and SQL Views are basically a prepared SQL statement and the access plan is stored for future reference...as far as native I/O a View is an unkeyed select/omit LF.

HTH

[kitvb1]

Re: DDS vs DDL

Thanks Tom

[kitvb1]

Re: DDS vs DDL

One of the advantages of using DDL is that you do not have to recompile the the programs after changing an index.

However, this can be a disadvantage because the program will still run but may return invalid results. eg. I removed a field in the key of the index, but left it in the the program's 'KLIST'. Program ran but found no recs to process. i.e. no warning that that the key no matches to the index.

Interesting... I wonder what whould happen if I just populate the field in the program with the correct value so that the chain would be theoritically successful, were the field in the key?

[kitvb1]

Re: DDS vs DDL

One of the advantages of using DDL is that you do not have to recompile the the programs after changing an index.

but one has to recompile if one changes the table

[tomholden]

Re: DDS vs DDL

but one has to recompile if one changes the table

yep...it's the same as adding fields,etc to a DDS file you have to recompile.