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Schema Advisor for Hybrid Relational-XML DBMS

Schema Advisor for Hybrid Relational-XML DBMS. Moro, Lim and Chang Presented by Wuliang Sun. Introduction. Data Persistence Relational Data XML ReXSA (Relational-XML Schema Advisor) Help data architects design database schemas for both relational and XML data. XML (benefits from XML).

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Schema Advisor for Hybrid Relational-XML DBMS

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  1. Schema Advisor for Hybrid Relational-XML DBMS Moro, Lim and Chang Presented by Wuliang Sun

  2. Introduction • Data Persistence • Relational Data • XML • ReXSA (Relational-XML Schema Advisor) • Help data architects design database schemas for both relational and XML data

  3. XML (benefits from XML) • XML • Self-documenting • Flexible • Widely accepted <account> This account is seldom used any more. <account-number> A-102 </account-number> <branch-name> Perryridge </branch-name> <balance> 400 </balance> <description> </description> </account> CREATE TABLE account (account_ID bigint NOT NULL PRIMARY KEY, accountX XML);

  4. Information Model • Business Artifacts • Contracts, resumes, reference letter • Schema Variability • Sparse data, optional attributes • Schema Evolution • Data Versioning

  5. Relational-XML Schema Advisor • Input: A logical data model annotated with information on business artifacts, schema variability and evolution, versioning, and a threshold t • Output: A Set of DDL Statements (relational-XML schema designs)

  6. Two phases for schema advisor • Score each entity and partition entities into relational type or XML type • Transforms the partitioned logical data model into table definition and XML schemas

  7. Score Entity Score = countFlexAttribs / countAttribs OR 1 if entity is business artifact Score(Person) = 0.4 Score(Faculty) = 0.4 Score(Resume) = 1

  8. Mapping Relationship • REL-REL Relationship • XML-REL Relationship • [A:XML] – 0..1 -<R> - 1 – [B:REL] • [A:XML] – N -<R> - 1 – [B:REL] • [A:XML] – 1 -<R> - N – [B:REL] • [A:XML] – M -<R> - N – [B:REL] • XML-XML Relationship • [A:XML] – 0..1 -<R> - 1 – [B:XML] • [A:XML] – N -<R> - 1 – [B:XML] • [A:XML] – N -<R> - M – [B:XML]

  9. Mapping Relationship (XML-REL) [A:XML] – M -<R> - N – [B:REL]

  10. Mapping Relationship (XML-XML) [A:XML] – N -<R> - 1 – [B:XML]

  11. Mapping Entity Hierarchies • Mapping Entities from a hierarchy • Mapping Relationships from a hierarchy • Parent Relationship • Children Relationship • Parent and Children Relationship

  12. Mapping Entity Hierarchies • Example of an entity hierarchy for students and courses in a university • Tables for merged courses and the respective student tables.

  13. Apply ReXSA • Threshold = 60%

  14. Apply ReXSA • *Resume and Education are defined as business artifacts

  15. Apply ReXSA • DDL statements for academic example

  16. Conclusion • User defined threshold is not rigid. • Mapping relationship from a hierarchy is not perfect. • Lack the measurement for the quality of mapping

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