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Benchmark ::implicit_grouping_neq : Corelated nested query with aggregate function in the return clause. The Correlation predicate contains an non-equality comparison.
(submitted at 2006-11-24)
Authors: Norman May (University of Mannheim)
Categories: XQuery,
Target: All systems
Engine type: persistent-storage main-memory
Measure: The measure targets the total execution time.
Result unit: Milliseconds

Query:
The naive evaluation of this query evaluates in nested-loops. This results in a quadratic increase in excution time when the document size is increased. More efficient evaluation strategies scale better.
Syntax: for $i in doc("items.xml")//item_tuple return <item> { $i/itemno } <count> { count(for $b in doc("bids.xml")//bid_tuple where $i/reserve_price lt $b/bid and $i/itemno eq $b/itemno return $b) } </count> </item>
Language: XQuery 1.0

Document:
The document creates a document that conforms to the DTD used for the XQuery Use Case REL.
Generator: Toxgene and reldata.tsl

Parameters:
Parameter num_items:
the number of items, this is the main scaling parameter
This parameter characterizes the: doc
Unit: None.
Values: 100 1000 10000
Distribution: uniform
Scale: ordinal
Parameter num_bids_per_item:
The number of bids per item.
This parameter characterizes the: doc
Unit: None
Values: 10
Distribution: uniform
Scale: ordinal

Methodology:
Running scenario: queryScale
Test the influence of the document size (which depends on parameter num_items) on the query execution time.
Parameter instantiation:
Name Value(s)
num_items 100 , 1000 , 10000
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