4.3 XQuery Updates

MonetDB/XQuery supports the W3C XQuery Update Facility with the following remarks:

• there is no support for the transform feature!
• rename uses a do rename .. into syntax instead of do rename .. as
• currently, each updating query executes in a single transaction (a la auto-commit). MonetDB/XQuery has no support yet for multi-query transactions. Note that in the XQUF, there is no proposed syntax (start transaction, abort, commit) for this yet either.
• the XQUF specifications leave many details of the fn:put() function to the implementation. Below we discuss how we handled those in MonetDB/XQuery.
• August 2007, W3C published a new and final call for the XQUF that makes some changes to the syntax (e.g. do insert became insert node). These changes are not supported yet in this version of MonetDB/XQuery.

In the remainder, we provide some background information of how transactions are implemented in MonetDB/XQuery.

• Transactions and Performance
• Check-pointing
• Snapshot Isolation Anomalies
• Locking and Page Fragmentation
• The put() Function