Should I choose explicit validation or implicit validation to validate the data?

Well. . .It depends on the source of the XML documents, the nature of your applications, and your business rules. If the XML documents are from a trusted source and the XML document knows its schema, implicit validation can be a good choice. If the XML document’s content is unknown, explicit validation is a good choice. For explicit validation, only one exact schema can be used to validate. For implicit validation, one or more schemas can be used to validate.

Which of Explicit validation and implicit validation is better in performance?

In general, explicit validation might have better performance than implicit validation. This is not because the actual explicit validation takes less time than the actual implicit validation. It is because the implicit validation requires DB2 to search the catalog tables to find the correct schemas that match the pair value. Explicit validation does not require searching the catalog tables.

When should I choose to validate within application feature in DB2 9?

In some situations, you might want to do validation within the application. For example, suppose that you have an on-line loan application program. Customers can log on and fill out their loan application on-line forms. You have a name field, birthday field, phone number field, and other fields in the on-line form. If the customer enters information that does not satisfy the schema constraints, such as entering character data into a numeric field, you want to validate the XML document on the client/application side. If the XML document is not valid, the application can interactively ask the customer to correct the entered data until the XML document is valid.

Is there any advantage of validating a document within application?

Like any computer algorithm, validation takes resources such as CPU and memory. Imagine that there are thousands of clients that insert massive XML documents to a server and the validation is done on the one server. Sometimes, a server does not have enough resources, and the clients have the necessary bandwidth. In this case, it can be a good idea to validate on the client. You can check http://www.ibm.com/developerworks/we...y/wa-dataflow/ for performance tricks for data-intensive applications

I know that we can validate the XML data against registered XML schema. But how does DB 2 manage XML schemas in general?

Applications can choose to validate XML documents against an XML schema to ensure valid data is stored in the database. To validate documents, DB2 needs access to the appropriate schema information. For this reason, DB2 has an XML schema repository (XSR) that maintains a copy of the XML schemas that might be used during validation. The XSR consists of a set of new catalog tables together with commands, stored procedures and APIs to register and manage XML schemas. You can check http://www.ibm.com/developerworks/xm...y/x-style.html for defining data validation rules in XML schema.