Tools for DDS to DDL migration

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Application development
Database
DB2
DB2 Universal Database
Oracle
Hi, My Profile: I have a legacy DDS defined DB2/400 database and my IT staff are telling me that for true SQL/ODBC access we either need to migrate the database over to DDL defined tables or add unique indexes to the existing DDS structure. My Question: Do we really need to alter the DDS database and if so are there any migration tools or utilities available to automate the process? Many thanks in advance.
ASKED: October 24, 2006  11:21 AM
UPDATED: October 26, 2006  1:29 PM

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You should not have to migrate your DDS to DDL or create special indexes. When running your SQL the system will look for similar LF’s or create an index on the fly using your where and order by statements. You can do SQL statements from the iSeries to get data off other platforms and should be able to run SQL from other platforms to get data off your iSeries.

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  • KevinBattreall
    You just have to journal the file if you are going to update the file through ODBC.
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  • LuisHernandez
    I am agree with the previous ideas. I believe you don?t need to migrate from DDS to DDL if you work in i5/as400. But you have to do this: 1) Journal the all files involved (to allow sql statement update) 2) Guarantee the pgms has access to the all PF file and LF files (to avoid create view at run time) 3) to know the experience of your IT team in the platform you are using or will (as an example If they are more familiar with Visual-Basic as a programming tool I understand -and share- why they would like to work in DDL). I never see a performance issue accessing DDS (for sure accessing DDL must be some microseconds faster) but you must keep in mind some issues that your DB Administrator will have: The DBA always checks the performance and if he ?sees? much I/O in some SQLCommand he can decide to create a View or Index. If he does not have experience in i5 he will need the support from other programmer to create the LF in i5. Mixed DDS and DDL need to be manage with careful. Other issues are if you will run pgms in other platform (eg. Windows-VB, connection) but you did not mention it (anyway you can access the data in i5 using sqlcommand even you use other platform). I think you probably need to discuss with your IT team why they think you ?must? migrate to DDL. I was wonder too what does meant ?true SQL/ODBC access? (specially the word ?true?). If the work to migrate is small and they feel (your team) comfortable with DDL (maybe they are more familiar with this technology) the migration probably should be done. The best
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  • Hoffman
    You may want to consider stored procedures on your AS400 to encapsulate the file IO and business logic. Your AS400 stored procedure could return a recordset or specific values back to your win app for processing.
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  • SteveCCNJ
    Consider downloading and reading the iSeries Modernization Redbook www.redbooks.ibm.com/abstracts/sg246393.html There are advantages to migrating, especially since IBM has abandoned any enhancements for DDS and will only enhance DDL. There are various objects and functions which cannot be described in DDS and which can only be addressed using DDL. Also, various SQL tools which connect to your iSeries data collections need DDL described data objects to give full functionality. Certain system tables (DB2 Catalog) are only maintained when defining the objects via DDL. But most importantly, IBM has a stated direction to do no new development in DDS and focus all its attention on DB2 DDL database support. It's time to move on, folks.
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  • Newbie400
    Thank you all for your insight - I didn?t think that I'd get such great input. As the resounding answer was that 'this shouldn't be a problem' I went back and reanalyzed what the REAL problem is. As it turns out our SQL based application uses two cursors, one for query and the other for updates. The problem surfaces on updates. The query results set doesn?t necessarily have unique rows and so we need a mechanism to be able to identify the selected row so that the update cursor can re-fetch the row for update. As we don?t have access to the native DB2 identifier we insist that the query set have a unique index (could be just a unique index based on timestamp). And so this issue is really application design and noting to do with DB2 infrastructure. Can?t really change the fundamentals of our application and so are looking at using sequences to create unique row identifiers that will only be used/maintained by our application. Thanks for all the help
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