Browse Benchmarks

Benchmark ::FLWR-COPY-LEVEL-ATTRIB : Descendant axis navigation
(submitted at 2006-06-26T18:00:00)
Authors: Ioana Manolescu (Gemo Group, INRIA Futurs, France) Philippe Michiels (Universiteit Antwerpen, Belgium) Cédric Miachon (BD, LRI, Université Paris Sud 11, France)
Categories: XQuery,Query Scalability
Target: All systems
Engine type: persistent-storage main-memory streaming
Measure: The measure targets the total execution time of an XQuery query returning attribute values from XML elements found at increasing depth in the document.
Result unit: Milliseconds

Query:

The query used in this micro-benchmark retrieves the value of @id attributes in all XML elements found at a given depth under the document root. The query concatenates all these attribute values inside a single returned (constructed) XML element.

For every integer n, the corresponding query, named FLWR-COPY-LEVEL-ATTRIB(n), is: 

     for $x in /t1/t2
     return <res>{ for $y in $x/*/*/.../*
                   return fn:data($y/@id) }
            </res>

The purpose of this query is to test the performance of increasingly deep navigation performed in a return clause. Query FLWR-COPY-LEVEL-ATTRIB(n) navigates 

n
levels under the 
/t1/t2
elements in the document, and retrieves the values of all 
@id
attribute nodes found at the target level. All values are concatenated in a single text node in a 
<res>
element.

In the target document, the size of the returned result is stable when 

n
varies from 
n=1
to 
n=9
. Therefore, the variation in the query execution is expected to be due to the navigation effort only.

Syntax:
Language: XQuery 1.0
Generator: generateQ21.java

Document:
The document flat2.xml is a tree such that:
  • the root is labeled t1
  • the root has 3268 children, labeled t2
  • each t2 child of the root (level 2 node) has 10 children, labeled with equal probability t3, t4, t5, ..., t12
  • each child of a t2 element (level 3 node) has 1 child, labeled with equal probability t3, t4, t5, ..., t12
  • ...
  • each level 12 node has 1 child, labeled with equal probability t3, t4, t5, ..., t12
  • each evel 13 element is a leaf.

More generally: the root has fanout 3268, the root's children have fanout 10 (bringing the number of nodes at level 2 to 32680), all elements whose level is between 2 and 12 have exactly one child, and the elements at level 13 have no children. (The document can be seen as a rooted collection of 32680 chains of parent-child elements, 10 deep.) At levels 3 to 13, node labels are uniformly distributed among t3, t4,..., t13.

The document's size is about 11 MB. The document is generated using the MemBeR document generator with the following configuration file:
Generator: MemBeR.Generator
Configuration file: Q21_exp_MemBeR_Generator_config.xml

Parameters:
Parameter n:
This is the number of consecutive child navigation steps in the query.
This parameter characterizes the: query
Unit: None.
Value Range: [ 1 .. 19 ]
Distribution: uniform
Scale: ordinal
Parameter docsize:
This is the size of the document.
This parameter characterizes the: doc
Unit: Byte
Values: 11009952
Distribution: uniform
Scale: ordinal

Methodology:
Running scenario: queryScale
Test the influence of the number of child steps on the total execution time. All other parameters are fixed.
Parameter instantiation:
Name Value(s)
n 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9
Download the micro-benchmark: [XML]
Micro-benchmark results