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Alert: Transforming Passive to Active DBMS IBM Almaden Research Centner CS561.

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Presentation on theme: "Alert: Transforming Passive to Active DBMS IBM Almaden Research Centner CS561."— Presentation transcript:

1 Alert: Transforming Passive to Active DBMS IBM Almaden Research Centner CS561

2 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.

3 Active vs Passive Tables For each passive table, the system generates an associated active table that logs all system-defined operations on the former

4 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

5 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

6 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


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