Schema Evolution publication categorizer

The days when a company could take its system offline for any kind of maintenance are rapidly disappearing. As businesses become global and move toward e-commerce, systems now have to be highly available because the cost of outage for corporations involved in e-commerce can easily reach millions of dollars per hour. Today, it is unlikely that the customer will come back if your systems are unavailable, they will simply give that business to your competitor whose systems are online. Online data reorganization, or the ability to allow users full access to the database during a data reorganization, improves the overall database availability and reduces planned downtime. Oracle9i introduced the online data redefinition capability that allows database administrators to perform not only data reorganization online but also data redefinition online. Each release of the Oracle database has introduced enhanced online data reorganization features such as creating indexes online, rebuilding indexes online, coalescing indexes online, moving index-organized tables (IOTs) online. The online data redefinition feature offers administrators unprecedented flexibility to modify table physical attributes and transform both data and table structure while allowing users full access to the database. This feature can also make the application upgrade process easier, safer and faster.