Alert: Transforming Passive to Active DBMS

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Alert Transforming Passive to Active DBMS

• IBM Almaden Research Centner
• CS561

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Minimal Extension of RDBMS

• Active Tables
• Only append new tuples
• Be aware what is new data
• Active Queries
• Specified over Active Tables
• Implement Via new cursor behavior fetch-wait
  a la blocking-read
• Idea never close on EOF, instead simply block
  and wait for new tuples to be inserted. See
  future data.

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Active vs Passive Tables

• For each passive table, the system generates an
  associated active table that logs all
  system-defined operations on the former

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Rule Model

• Rule named active query
• Advantage
• Rule and query unified so can compose both
  on views.
• Activate Rule
• open query and set up fetch-wait cursor
• specify transaction modes at activation time

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Execution

• Store all rule definitions and activations in
  catalog
• Monitor for all active queries on active tables
• If several apply, send them to conflict resolver
• Monitor subsystem
• Optimize concurrency first check condition if
  positive, then acquire lock to continue on rule
• Keep track for each query, what tables it applies
  to
• Simple indexing to keep track of where data was
  last seen, vs what is new data

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Conclusion

• Simple Rule Model Basically reuse query parser
  and optimizer
• Unify queries and rules
• Main idea is a new style of cursor read
  blocking kind
• Otherwise, make decisions that naturally fit
  existing technology