XML and Databases Exercise Session 10 courtesy of Ghislain Fourny © Department of Computer Science | ETH Zürich

Previously, in XML&Databases Document Well-Formedness (Validation) Data Model Processing XML with namespaces (XML Schema) optional XDM XQuery <a/>

Query Plan

java –jar mxquery.jar -f myquery.xquery --explain --discardResult Query Plan in MXQuery java –jar mxquery.jar -f myquery.xquery --explain --discardResult

Query Plan

Query Plan

Query Plan

Query Plan

Query Plan

Execution cost We take the number of processed nodes as a metric.

Query Plan Execution cost 6

Query Plan Execution cost 6 + A( )

Query Plan Execution cost 6 + A( 10 )

Query Plan Execution cost 6 + A( 10 B(7) )

Query Plan Execution cost 6+10A+7AB

Redundancies? Execution cost 6+10A+7AB

Redundancies? Execution cost 6+10A+7AB new: 8+9A+7AB

Redundancies? Execution cost 6+10A+7AB new: 8+9A+7AB better as soon as A>2

Query Plan

Hope to see you next week!