1. Temporal DBMS JD Pack Software Architecture

2. Introduction  Conventional databases store “now” data  Can store huge amounts of data, but only data in the present  What about systems that might require past and even future data storage? (banking, inventory, geographical, medical)  Temporal DBMS  Databases designed to handle time-dependent data  Supported using temporal data models, temporal SQL  Key aspects: valid time, transaction time

3. Valid Time  Period of time which data is considered to be valid  Storing historical data  Retrieve data later, rather than overwrite with new information  Data can be valid as past, present, or future  Unknown time values are marked as ∞ EmpID Name Department Salary ValidTimeStartValidTimeEnd 10JohnResearch1100019851990 10JohnSales1100019901993 10JohnSales120001993INF 11PaulResearch1000019881995 12GeorgeResearch105001991INF 13RingoSales155001988INF http://www.timeconsult.com/TemporalData/TemporalDB.html

4. Transaction Time  Time period which data is considered to be true  Only occurs in past or present data  Allows DBMS to be presented as states  Temporal SQL can be used to pull data within a specified time frame that shows when the data was asserted  Useful for taxes or auditing NameCityValidStartValidEndT.StartT.End John Doe, Smallville, 3-Apr-1975, ∞, 4-Apr-1975, 27-Dec-1994 John Doe, Smallville, 3-Apr-1975, 26-Aug-1994, 27-Dec-1994, ∞ John Doe, Bigtown, 26-Aug-1994, ∞, 27-Dec-1994, 2-Feb-2001 John Doe, Bigtown, 26-Aug-1994, 1-Jun-1995, 2-Feb-2001, ∞ John Doe, Beachy, 1-Jun-1995, 3-Sep-2000, 2-Feb-2001, ∞ John Doe, Bigtown, 3-Sep-2000, ∞, 2-Feb-2001, 1-Apr-2001 John Doe, Bigtown, 3-Sep-2000, 1-Apr-2001,1-Apr-2001, ∞

5. Bitemporal Relations  Relationship between Valid & Transaction Time  Provides both historical and rollback data  Storing data using this method allows access to snapshots of the database http://www.timeconsult.com/TemporalData/snapshot.gif

6. Current Temporal Implementations  Oracle Workspace Manager  TimeDB  PostgreSQL  Teradata  Anchor Modeling  IBM DB2  OSIsoft (PI System)

7. Limitations  Schema Evolution  It is vital that data be stored using the schema version in which it originally appeared  The smallest of changes to the history of a value have to be redone by hand for each version of the schema  Time standards  SQL2 standards are poorly designed and suffer from range limitations and efficiency  Inconsistency  Lack of coherent architectures, commercialization  Performance

8. Example – MediaWiki Schema Wiki Commons

9. Sources  http://temporal.projects.pgfoundry.org/reference.html http://temporal.projects.pgfoundry.org/reference.html  https://cs.arizona.edu/~rts/pubs/LNCS639.pdf https://cs.arizona.edu/~rts/pubs/LNCS639.pdf  http://www.timeconsult.com/TemporalData/TemporalDB.html http://www.timeconsult.com/TemporalData/TemporalDB.html  http://www.cs.arizona.edu/people/rts/tdbbook.pdf http://www.cs.arizona.edu/people/rts/tdbbook.pdf  http://www.mediawiki.org/wiki/Manual:Database_layout http://www.mediawiki.org/wiki/Manual:Database_layout