xml labling and query optimization sigmod2009 2009-7-3
TRANSCRIPT
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XML Labling and Query Optimization
Sigmod2009 2009-7-3
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Outline
XML DBS related researches in sigmod2009 DDE labeling Scheme XQuery Optimization conclusion
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sigmod2009 Research Session 16: Query Processing on Semi-structured Data
Cost Based Plan Selection for XPathHaris Georgiadis (Athens University of Economics and Business)Minas Charalambides (Athens University of Economics and Business)Vasilis Vassalos (Athens University of Economics and Business)ROX: Run-time Optimization of XQueriesRiham Abdel Kader (University of Twente)Peter Boncz (CWI)Stefan Manegold (CWI)Maurice Van Keulen (University of Twente)
Research Session 19: Semi-structured Data Management DDE: From Dewey to a Fully Dynamic XML Labeling Scheme
Liang Xu (National University of Singapore)Tok Wang Ling (National University of Singapore)Huayu Wu (National University of Singapore)Zhifeng Bao (National University of Singapore)Simplifying XML Schema: Effortless Handling of Nondeterministic Regular ExpressionsGeert Jan Bex (Hasselt University and Transnational University of Limburg)Wouter Gelade (Hasselt University and Transnational University of Limburg)Wim Martens (Technical University of Dortmund)Frank Neven (Hasselt University and Transnational University of Limburg)FlexRecs: Expressing and Combining Flexible RecommendationsGeorgia Koutrika (Stanford University)Benjamin Bercovitz (Stanford University)Hector Garcia-Molina (Stanford University)
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Outline
XML DBS related researches in sigmod2009 DDE labeling Scheme XQuery Optimization conclusion
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Dewey labeling Concatenation of its parent
labeling and local order helpful for Keyword search High cost of relabeling for
dynamic XML document
Is there a labeling scheme which not only has compact size and high query performance but also completely avoids relabeling?
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DDE Labeling (1) Character
Can completely avoid relabeling Efficiently support query Not add the length of labeling Only the definition of “preorder”
Preorder
labels A :a1.a2 … am and B : b1.b2 ...bn
A≤dde B if
DDE: From Dewey to a Fully Dynamic XML Labeling SchemeLiang Xu, Tok Wang Ling School of Computing National University of singapore
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DDE Labeling (2) Leftmost insertion insert before node A : a1.a2 … an (A is the first child ) a1.a2
… (an-1) ->this node. Rightmost insertion insert after node A : a1.a2 … an (A is the last child ) a1.a2 … (an + 1) -> this node. Insertion below a leaf node insert below a leaf node A :a1.a2 … an a1.a2 … an .1 -> this node. Insertion between two consecutive siblings insert between A and B A+B->this node
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DDE Labeling (3)--example
AB
C D
H G FE
1
1.-1
1.1 1.2
1.0
1.1.1
1.1.2 1.2.1 1.2.2 1.2.3
I
3.3.5
3.3.5.1
5.4.82.2.31.1.1.1
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DDE Labeling (4) AD relationship A/m is an ancestor of B/n if m<n and
PC relationship A/m is the parent of B/n if m=n and A/m is an ancestor of B/n
Document order A precedes B if A<ddeB
Sibling relationship A is the sibling of B if
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CDDE labeling(1) Compact DDE Enhance the performance of DDE for insertion Relationship between them
CDDE label ->DDE label
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CDDE labeling(2)—example
AB
C D
H G FE
1
1.-1
1.1 1.2
1.0
1.1.1
1.1.2 1.2.1 1.2.2 1.2.3
I
3.1.5
-1.3.3.5.1
5.1.82.1.31.1.1.1
K J
-2.3.3.5.3 -1.3.3.5.2
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Outline
XML DBS related researches in sigmod2009 DDE labeling Scheme XQuery Optimization conclusion
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Optimization of XQueries Take Join Graph as input and care the
correlations Interleave optimization and execution steps Use sample to estimate the cost Use index to get sample Use Chain Sampling to get optimal path
ROX: Runtime Optimization of XQueriesRiham Abdel Kader University of Twente Enschede, The Netherlands
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Join Graphs
let $r := doc(“auction.xml”)
for $a in $r//open auction[./r
eserve]/bidder//personref,
$b in $r//person[.//education]
where $a/@person = $b/@id
return $a
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Related notation CutOff Sampled Operators :return a sample with size l :return partial execution results of the operator OP with s
ize l Weight of edge
cost(p)=cost(p’)+est*card(source) ÷T Sf(p)=est/T
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Chain Sampling Chain Sampling makes ROX avoid local
minimum due to correlations only explore those paths that branch from the
edge with the smallest weight Find the optimal path pi
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Example for Chain Sampling
[cost, sf ](p1) = [1500, 1.5][cost, sf ](p2) = [2000, 1][cost, sf ](p3) = [1300, 0.1][cost, sf ](p4) = [3200, 2]
V2 V3
V5
V1 V4
V7
V6 V8
p1 p2
p3
p2
p3
p4p3 is selected
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Optimization Algorithm
Reduce the intermediate results exploring the search space by Chain Sampling Find the optimal path interleave optimization and execution steps
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Illustration let $d := doc(“xmark.xml”)for $o in $d//open auction[.//current/text() < 145],$p in $d//person[.//province],$i in $d//item[./quantity = 1]where $o//bidder//personref/@person = $p/@id and $o//itemref/@item = $c/@idreturn $a
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Illustration(续 )
p1
p1
p1
p1p1
p1
p2
p2p2
p2p2
p2
8
7
6
54
3
9
1011
1213
14
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Outline
XML DBS related researches in sigmod2009 DDE labeling Scheme XQuery Optimization conclusion
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conclusion
DDE and CDDE
They are tailored for both static and dynamic XML documents.
ROX: Runtime Optimization
To reduce the number of intermediate results
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