Schema Evolution publication categorizer

Telecom Databases need very high availability for
both read and write transactions. Thus it is desired that
not even schema changes are allowed to block any type
of transactions. We show in this paper a method to handle
schema changes which is based on a transaction oriented
change with the aid of triggers. The old and the
new schema can be used concurrently so it is never necessary
to block any transactions.
A nice feature of the method presented in this paper
is that it is easy to integrate into an already existing
DBMS.
This functionality is rarely, if ever, found in neither

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.

DB2 V8 begins the process of making it easier to implement database changes with fewer steps and less downtime. IBM calls the changes being made to DB2 to facilitate simpler and quicker database changes \"online schema evolution\". For example, as of V8, you can change a CHAR column to a larger size simply using ALTER. The remainder of this article will focus on the improved schema changes supported by DB2 Version 8.

DB2 provides native XML storage, indexing, navigation and query processing through both SQL/XML and XQuery using the XML data type introduced by SQL/XML. In this tutorial we focus on DB2s XML support for schema evolution, especially DB2s schema repository and document-level validation.