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AGGREGATE PATH INDEX FOR INCREMENTL WEB VIEW MAINTENANCE

AGGREGATE PATH INDEX FOR INCREMENTL WEB VIEW MAINTENANCE. Author: Li Chen and Elke Rundensteiner Department of Computer Science Worcester Polytechnic Institure Presented by Pengpeng Lu. OUTLINE. OBJECTIVE INTRODUCTION MAINTENANCE STRATEGY MAINTENANCE APPROACH EVALUATION CONCLUSION.

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AGGREGATE PATH INDEX FOR INCREMENTL WEB VIEW MAINTENANCE

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  1. AGGREGATE PATH INDEX FOR INCREMENTL WEB VIEW MAINTENANCE Author: Li Chen and Elke Rundensteiner Department of Computer Science Worcester Polytechnic Institure Presented by Pengpeng Lu

  2. OUTLINE • OBJECTIVE • INTRODUCTION • MAINTENANCE STRATEGY • MAINTENANCE APPROACH • EVALUATION • CONCLUSION

  3. OBJECTIVE • DEVELOP EFFICIENT WEB VIEW MAINTENANCE TECHNIQUE Web Web1 Web2 Web3 Web6 Web7 Web4 Web5

  4. INTRODUCTION • WEB DATA: • DYNAMIC • NO “STRICT SCHEMA” FOR XML FILE • WEB DATA NOT EASY TO BE SEPARATED • WEB VIEW MAINTENANCE APPROACHES • RE-COMPUTE FROM SCRATCH---NOT EFFICIENT • INCREMENTAL MAINTENANCE---EFFIEIENT • AGGREGATE PATH INDEX (APIX)

  5. DOM TREE STRUCTURE (XML DOCUMENT) MAINTENANCE STRATEGY

  6. MAINTENANCE STRATEGY • WEB VIEW SPECIFICATION (XQL) • Define web view favorite_entries as • /E-mail/shop/[@category=“toy”]/entry[@maker=“ASE” and • @quantity>0 and price <$20 and item=“book”] QUERY TREE APIX INDEX: E S /E-mail/shop/[@category=“toy”]/entry[@maker=“ASE” and @quantity>0 and price <$20 and item=“book”] e m q p i

  7. MAINTENANCE APPROACH • PATH PATTERN EVALUATION • TWO-STEP: • PATH PATTERN • EVALUATION • Store “qualified” • objects into APIX • PREDICATE VALUE • EVALUATION /E-mail/shop/[@category=“toy”]/entry[@maker=“ASE” and @quantity>0 and price <$20 and item=“book”]

  8. MAINTENANCE APPROACH • PREDICATE VALUE EVALUATION • View Object: • Path Pattern Satisfiable • ER Value is True • Data Update Operations: • Insertion • Deletion • Change Evaluation Vaue (ER): True/1 False/0

  9. MAINTENANCE APPROACH • CHECK IRRELEVANT CASES: • Query Irrelevant Update • Value Irrelevant Change • Irrelevant Deletion • Example: <Ins, &5, “entry”, &15> RELEVANT CASES: Example: <Ins, &11, “item”, &36>

  10. COST ANALYSIS <Ins, &15, “item”, &39> Costnaive=CE +Cs+Cc+Ce+ Cm+Cq+Cp+Ci CostAPIX=1+(C’m+C’q+C’p+C’i) /24-1

  11. ADVANTAGE • Prune the traversal space---reduce the accesses to base data • Cache a reduced set of relevant objects---save index space DISADVANTAGE APIX index table cost extra space for the columns

  12. CONCLUSION • APIX STRUCTURE WAS PROPOSED FOR • INCREMENTAL WEB VIEW MAINTENANCE • THROUGH COST ANALYSIS, APIX FOR WEB • VIEW MAINTENANCE DEMONSTRATED • ENHANCED EFFICIENCY

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