Working with the Database - eXist: A NoSQL Database and Application Development Platform - page 101

Figure 5-3. The XQuery dialog in eXist's Java Admin Client tool
You can type queries (or open them from files), view the results, and even get a trace
of their execution.
Updating Documents
A database wouldn't be of much use if you couldn't update its contents. Of course,
you can always replace complete documents with new, updated ones, but for larger
documents that's not very efficient. Therefore, XML databases—and eXist is no
exception—provide mechanisms to update specific nodes within XML documents
directly.
A document update in eXist has a relatively large overhead. It creates a transaction,
updates the XML, and updates the relevant indexes. This makes updating expensive.
For this reason, try to do as much as possible in a single update. For instance,