Oracle’s DCT is of great value because you are buying a methodology on downsizing by the world’s most successful database company. You are also buying this methodology from a company that directly benefits—in sales of their product—whenever a downsizing or migration effort is undertaken; Oracle wants migrations to their platform to succeed. Along with this methodology, you are purchasing a set of tools that, although requiring programming expertise, help enforce and facilitate the methodology down to the coding level. With Oracle’s DCT, you get the best of both worlds: a methodology tool and a conversion tool.

Summary

As stressed in this chapter, a successful migration is more of a managerial effort than a technical effort. Once you have a solid conversion plan in place, a way to track progress, and the support of human resources from both the source system and the target system, you have fought half the battle.

In general, migrations are very difficult because you have to translate a different mind-set into a new one. Even if you’re moving across relational platforms, ways of doing things in one database environment and powerful shortcuts have influenced the development process and will need to be examined in the migration. Sometimes, rewriting a huge amount of code that no one understands is more costly than simply building a new system.

Even though the front-end will be the only direct evidence the user has of a migration, the most important and time-consuming task for most systems migrations is the translation of data. The farther apart the source and the target system are in database philosophies, the more difficult this translation will be.

Even though it wasn’t mentioned in this chapter, migration efforts often hinge upon how well you can tune and configure the new instance(s) of the Oracle database on which the source data will reside. Mapping data is only the beginning of the migration process; once the data is there, you must unlock those features of Oracle that will enable the new target system to perform as well or better than the old system, and thus justify the cost of the migration effort itself.