Database Reference
In-Depth Information
First, some of the lower bounds for various XML data exchange problems are already wit-
nessed in the relational case. Since relational databases can be represented as particularly
simple XML documents, every now and then we shall obtain lower bounds for free. Sec-
ond, we shall see that under some restrictions, XML data exchange can be performed by
translating XML into relations and then using relational techniques. However, for that to
happen, restrictions need to be imposed both on schemas and on schema mappings.
