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AGGREGATE PATH INDEX FOR INCREMENTL WEB VIEW MAINTENANCE

This paper presents an efficient technique for maintaining web views through an innovative Aggregate Path Index (APIX) strategy. Traditional methods such as recomputing from scratch are inefficient, especially with dynamic web data lacking strict schemas. Our approach utilizes incremental maintenance, allowing for improved resource allocation and reduced access to base data while evaluating path patterns and predicate values. Through cost analysis, we demonstrate how APIX enhances the efficiency of web view maintenance, making it a significant advancement in the field of dynamic web data management.

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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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