1 / 23

Misconceptions About Real-Time Databases

Misconceptions About Real-Time Databases. IEEE Computer Authors: John Stankovic, Sang Hyuk Son, Jorgen Hansson Presented By: Patti Kraker. Definitions. Real-time database is a database system Queries Schemas Transactions Concurrency control support Storage management. Definitions.

edmund
Download Presentation

Misconceptions About Real-Time Databases

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Misconceptions About Real-Time Databases IEEE Computer Authors: John Stankovic, Sang Hyuk Son, Jorgen Hansson Presented By: Patti Kraker

  2. Definitions • Real-time database is a database system • Queries • Schemas • Transactions • Concurrency control support • Storage management

  3. Definitions • Timing constraints associated with transactions • Not every transaction, but some • Data valid for specific time intervals

  4. Definitions • Time semantics on data • E.g. sensor data, stock market prices • Semantics indicate valid for certain time period • In a real-time database • Validity interval part of database schema

  5. Definitions • Transaction Correctness • Absolute time consistency • Individual data is temporally valid to acceptable degree of accuracy • Relative time consistency • Multiple data items updated within specified time interval of each other • E.g. time and pressure

  6. Misconceptions • Real-time systems synonymous with speed • Current database technology can be used in real-time database systems

  7. Misconceptions/Research • Real-time database properties: temporality, predictability, specialization • Research areas for real-time databases

  8. Real-time systems synonymous with speed

  9. Hardware advances • Hardware advances will address real-time database requirements • Parallel processing • Does not mean meet timing constraints • Inc. size and complexity • Hardware alone not ensure data accurate

  10. Hardware advances • Sum up hardware advances • Transaction that uses obsolete data more quickly is still incorrect

  11. Advanced DB technology • Advancing Standard Protocols • Better buffering, faster commit protocols, better query processing • Can not guarantee deadlines or valid data • Required advances include: • time cognizant protocols, commit processing • transaction scheduling, logging, recovery

  12. Advanced DB technology • Sum up advanced db technology • These protocols better at supporting real-time transaction and data correctness than standard database protocols that simply go fast.

  13. Real-time = Fast • Fast computing: Aim to minimize response time of transactions • Real-time computing: Aim to meet timing constraints and data validity of transactions and keep database current • Need time cognizant protocols

  14. Current DB technology can solve real-time problems

  15. Traditional databases • Traditional databases can handle real-time • Can define field that contains validity interval • Every transaction must check this field to ensure absolute and relative validity • Can run earliest deadline scheduling through priority of transaction

  16. Traditional databases • By adding those features, moving toward real-time db • More efficient to build them into system than force fit traditional db

  17. Db in main memory • Placing a conventional database in main memory is sufficient (non-real-time db designers) • Does eliminate disk delays • Still unpredictable: • Delays due to blocking on locks • Transaction scheduling • Stolen processing time to handle external interrupts

  18. Db in main memory • Sum up current db technology • Increases in performance can not completely make up for lack of time-cognizant protocols

  19. Real-time DB in main memory • A real-time db must reside totally in main memory (real-time db designers) • Reasons: to increase speed, avoid seek and rotational delays of disks • Primary issue I/O • Minimize response time, maximize throughput, maintain fairness • Typical disk scheduling algorithms are First-Come-First-Served (FCFS), Shortest-Seek-Time-First (SSTF), etc.

  20. Real-time DB in main memory • Sum up real-time db in main memory • Since deadline and importance of transaction are not considered when disk request are scheduled, timeliness of transaction is jeopardized.

  21. Start of real-time databases • Real-time databases emerged from: • Telecommunications, manufacturing, and avionics applications • Conventional databases not adequate

  22. Research of real-time db • Increased audio and video applications • More research problems being addressed

More Related