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abhijitvyas 51 posts Joined 08/06
05 Mar 2007
Challenges of migration from oracle to Teradata

well we are in the planning phase of Migratiopn Project from Oracle to Teradata. can anyone kindly Points out Majore Business challenges in terms of Data modeling or any other and Technical challenges assosiated with it.this is kind of an urgent so appritaite the quick ResponseRegardsAbhijit

joedsilva 505 posts Joined 07/05
05 Mar 2007

Some of the points to ponder are. (These are not necessarily the "Golden Rules", just pointers, the right combination to choose would largely depend on the scenario)Try to take the data model to something closer to 3NF (This is a tough stuff to sell to customer who has no clue and is mostly worried about saving cost/effort on migration and lacks far sight...), revisit the stored procs ( A Good deal of TD warehouses do a good job even though they don't have stored procs ).Materialized views -> JIsRemember that PK <> PI in TD and choose your PIs wisely (This is one place where lots of mistakes are made, Oracle folks tend to choose PI = PK). Actually it's worth dragging the Dev folks to a training class just to get that difference into their minds.Try to use JIs and it's variants where you have concerns over performance without the necessity to denormalize.Check for compatibility of data types between source and target platforms. ( check on boundary/max values etc) Compression on tables can save a lot of space, so it might be worth the effort to do some Data Demographics on the existing Oracle tables to see what data can be compressed.You may notice that TD lacks quite a bit of "common sql functions" that was there in Oracle. In that case you might want to check on installing Oracle UDFs available from TD site.Then there are other DBA stuffs to think about (using of profiles, roles, arranging databases and users into appropriate hierarchy, managing permissions using them ...etc..etc)last, but not the least make sure to test extensively the applications that use ODBC/JDBC to connect to database extensively (There could be quite a bit of surprises).I am sure others can add more.

Luckyhansh 30 posts Joined 08/06
18 Apr 2007

As PK<>PI, great effort should be done for Applications, not just Database.Also sql scripts should be cared especially when your sql doesn't follow ANSI :-)Terdata have a little difference from Oracle( for example ,update)

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