Tamino XML Server Version 9.7
 —  Advanced Concepts  —

Operations

Apart from integrity rules which check for the violation of constraints, a second concept exists to ensure referential integrity: triggers. Referential triggers are used to invoke operations when a data record is inserted, updated, or deleted. For example, when a record representing a purchase order is deleted, it is also necessary to delete the records containing the individual order lines. This can be achieved with triggers.

For XML documents, however, the concept of triggers to guarantee referential integrity is not as essential as it is for SQL. The reason is that a complex business document such as a purchase order is not – like in the relational world – fragmented into flat records but is instead stored as a single structured document. When such a purchase order is deleted, the order lines vanish, too, because they are contained in the same document.

However, there are scenarios where we might want to execute additional operations when documents are inserted, updated, or deleted:

The operations that are possible in the context of insert, update, or delete operations by far exceed the scope of traditional referential triggers. In particular, they can modify data outside the database, data that resides somewhere else.

Similar to integrity rules, the best place for the implementation of such general operations is the application or some appropriate middleware.

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