XML Labling and Query Optimization Sigmod

Outline XML DBS related researches in sigmod2009 DDE labeling Scheme XQuery Optimization conclusion

sigmod2009 Research Session 16: Query Processing on Semi-structured Data Cost Based Plan Selection for XPath Haris 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 XQueries Riham 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 Expressions Geert 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 Recommendations Georgia Koutrika (Stanford University) Benjamin Bercovitz (Stanford University) Hector Garcia-Molina (Stanford University)

Outline XML DBS related researches in sigmod2009 DDE labeling Scheme XQuery Optimization conclusion

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 schemewhich not only has compact size and high query performance but also completely avoids relabeling?

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 Scheme Liang Xu, Tok Wang Ling School of Computing National University of singapore

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

DDE Labeling (3)--example AB C D HGF E I

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< dde B Sibling relationship A is the sibling of B if

CDDE labeling(1) Compact DDE Enhance the performance of DDE for insertion Relationship between them CDDE label ->DDE label

CDDE labeling(2) — example AB C D HGF E I KJ

Outline XML DBS related researches in sigmod2009 DDE labeling Scheme XQuery Optimization conclusion

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 XQueries Riham Abdel Kader University of Twente Enschede, The Netherlands

Join Graphs let $r := doc(“auction.xml”) for $a in $r//open auction[./r eserve]/bidder//personref, $b in $r//person[.//education] where = return $a

Related notation CutOff Sampled Operators : return a sample with size l :return partial execution results of the operator OP with size l Weight of edge cost(p)=cost(p’)+est*card(source) ÷T Sf(p)=est/T

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

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] V2V3 V5 V1 V4 V7 V6V8 p1p2 p3 p2 p3 p4 p3 is selected

Optimization Algorithm Reduce the intermediate results exploring the search space by Chain Sampling Find the optimal path interleave optimization and execution steps

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 = and = return $a

Illustration( 续 ) p1 p

Outline XML DBS related researches in sigmod2009 DDE labeling Scheme XQuery Optimization conclusion

DDE and CDDE They are tailored for both static and dynamic XML documents. ROX: Runtime Optimization To reduce the number of intermediate results