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Compiling Mappings to Bridge Applications and Databases

Compiling Mappings to Bridge Applications and Databases. Melnik, Adya and Bernstein @Microsoft Research. Introduction. Application Model VS Database Model Reasons Approaches Client side mapping layer Providing updatable views on DB ADO.NET Entity Framework Declarative mappings

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Compiling Mappings to Bridge Applications and Databases

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  1. Compiling Mappings to Bridge Applications and Databases Melnik, Adya and Bernstein @Microsoft Research

  2. Introduction • Application Model VS Database Model • Reasons • Approaches • Client side mapping layer • Providing updatable views on DB • ADO.NET Entity Framework • Declarative mappings • Bidirectional views • Query view : app = view(DB) • Update view: DB = view(app)

  3. Mapping Approach • Mapping Specification • Entity SQL + XML • Mapping fragment: • Mapping Compilation • Bidirectional views • Query views + Update Views • Properties • Entities = QueryViews(Tables) • Tables = UpdateViews(Entities) • Entities = QueryViews(UpdateViews(Entities)) - Roundtripping criterion • Execution • ▲Tables = ▲ UpdateViews(Entities, ▲ Entities) • ▲ Tables = ▲ UpdateViews(QueryViews(Tables), ▲ Entities) • Merge Views : SupdX Sold→ Snew

  4. Mapping Compiling Problems • Data roundtrips • map o map-1 = Id(C) • u subset map subset q-1 • Merge Views • SupdX Sold→ Snew • Biparite Mappings • map = f o g-1 • f : C → V • g : S → V

  5. View Generation • Overview • Query view • q = f’ o g, where f’ : V → C • Update View • Schema partition • Merging view • An example

  6. View Generation • Partitioning Schema • Mapping language dependent • Goals: Allowing expressing each fragment query in map as a union query over the partitions

  7. View Generation • Reconstructing partitions • Injectivity holds only if the partitions can be reconstructed from the views

  8. Conclusion • A new mechanism supporting updatable views • Formulating mapping compilation problems and algs. • Implemented in Commercial Product

  9. Thank You !

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