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