Forum Topics

1
Forum Topics

• OMG Roundtable Dec. 11, 2007

2
Background

• Forum is part of the ODBMS.ORG
• Moderated by Dr. Roberto Zicari
• Started on 10/16/07 (last post 12/8/07)
• Great place to discuss and post issues
• http//developer.db4o.com/forums

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Main Topics Discussed

• Query Language/ Object Store API
• Requirements/scope of the QL/API?
• Adoption other options related issues
• How to define semantics?
• Required optimizations? How to express their
  semantics?
• Other DB Essential Facilities
• Threading, Triggers, Views
• Client/Server, ACID, Replication, Synchronization
  of clients
• Object Store Model
• Do we need a model?
• What are the goals/scope of this effort/model?
• Specific requirements for model?

4
Object Store QL/API Requirements

• Easy to adopt
• Programming Language integrated (NQ) e.g. Java,
  Ruby, LINQ
• Existing JDO, JPA, HQL, EJB, current vendors
  QLs, de-facto
• Expressive power
• Ability to do insert, delete, update (or
  retrievemodify)
• Ability to support collections of different types
  ( lang. / user defined)
• Strong type-checking/ Type safe
• Support transactions
• Integration with PL control structures, e.g.
  loops, if_then)
• Integration with PL abstractions, e.g.
  procedures, methods, modules
• Expressive of DB abstractions, e.g. triggers,
  updatable views, Integrity constraints
• As expressive as SQL and more i.e. able to
  express UML diagrams e.g. associations,
  collections

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Object Store QL/API Requirement (continued)

• Expressive power (continues)
• DB Schema language that corresponds to UML
• Query optimizations (with semantics), e.g.
  indexing, activation
• Bindings to prominent OO PLs
• Need to be complete (define!)
• How to define semantics?
• We need to clearly define semantics for the
  QL/API
• One way based on a model
• Any other way?
• based on sets of compliance tests ?
• Reference implementations
• Define in Phases? Whats in phase1?
• Dr. Subieta says 1-8 of above requirements

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Object Store API Optimizations

• Requirements
• Indexing,
• Transparent Persistence (activation/store)
• Caching, Pipelining
• Handling large collections
• Aggregates
• sum, avg., there exists, min, max, etc.
• Adapt to different storage technologies
• Optimize existing PLs
• Define Behavior. How?

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Other DB Essential Facilities

• Concurrent Access and Client/Server support
• Multi-threading
• Client/Server protocol
• Concurrency Control
• Rollbacks
• Integrity (in face of failures)
• Replication between databases
• Synchronization of clients
• Interoperability facilities (translation to/from
  relational dbs and XML repositories)
• Administration (de-fragmentation, meta info, etc.)

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Object Store Model

• Do we need a model?
• Mike Card its one of the major criticism of
  OODBs
• Dr. Subieta needed to define semantics,
  consistency
• Can we do with compliance tests instead?
• What are the goals/scope of this effort/model?
• Support a strong, consistent QL/API
• Define operational semantics for the API
• Define expected behavior for optimization,
  facilities

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Summary

• Whats the strength of Object Database? How are
  they used?
• What do customers need from them? How is it
  different than Relational DBs?
• Do we need to compare with SQL? Schemas? UML?
• Requirements for QL more? drop some?
• Defining semantics besides a model is there
  another way?
• Programming Language Integrated QL/API or not?
• A theoretical model needed or not? Whats its
  purpose? Different model? Why?
• Other optimization areas? How do we define
  expected behavior?
• Additional Facilities?
• Do it in 1 phase or more?
• How do we increase probability of adoption?
• Approaches?
• Mechanisms?
• What are the inhibitors?