Active and main memory database

Active and main memory by Preetam

1. ACTIVE AND MAIN MEMORY DATABASE By Preetam Rajkhowa Roll no 21 MCA 4 th Semester CCS, DU

2. CONTENTS INTRODUCTION DEFINITION ADVANTAGES AND DISADVANTAGES APPLICATIONS CURRENT RESEARCH FUTURE WORK CONCLUSION REFERRENCE

3. INTRODUCTION ACTIVE DATABASE: Active database are database systems that supports mechanisms that enable them to respond automatically to events that are taking place either inside or outside the database system itself by supporting the specification and implementation of reactive behaviour. The reactive behaviour resides on rules which integrate cause with an expected effect.     MAIN MEMORY DATABASE: Main Memory Database resides permanently in the Main Memory of the system. There is a backup copy of the database that is stored on the disk. It primarily relies on main memory for computer data storage and is contrasted with database management systems that employ a disk storage mechanism. It is also known as In Memory Database.  

4. DEFINITION OF ACTIVE DATABASE It is a type of database system that uses Event Driven Architecture often in the form of ECA rules which responds to conditions both inside and outside the database. They are invoked by synchronous events generated by user or application programs as well as external asynchronous data change events such as a change in sensor value or time.

5. ACTIVE RULES/PRODUCTION RULES They are stored programs which are automatically triggered when an event occurs. Triggers can be written in response to Data Manipulation Language (DML) or Data Definition Language (DDL) or the Database Operations . The desired reactive behaviour is expressed in terms of Production Rules which are designed and stored in the Database. The benefit is that the rules can be shared by many application programs and the database can optimise their implementation.

6. FEATURES OF ACTIVE DATABASE It possess all the concepts of a conventional database i.e. data modelling facilities, query language etc. It supports all the functions of a traditional database like data definition, data manipulation, storage management etc. It supports definition and management of ECA rules. It detects event occurrence. It must be able to evaluate conditions and to execute actions. It means that it has to implement rule execution.

7. DEFINITION OF MAIN MEMORY DATABASE Main Memory database is the database system that primarily relies on main memory for computer data storage. They are faster than disk-optimized databases because disk access is slower than memory access, the internal optimization are simpler and execute fewer CPU instructions.

8. FEATURES OF MAIN MEMORY DATABASE Data can be directly accessed and uses shared memory architecture. There are no network overhead or data copies. They are tightly coupled. They are highly concurrent. Fully ACID transactions.

9. ADVANTAGES OF ACTIVE DATABASE Active database systems enhance traditional database functionalities with powerful rule processing capabilities. Triggers in active database enable a uniform and centralized description of the business rules relevant to system. It facilities the maintenance of the business rules. The layered approach is beneficial for active object oriented databases if the base system is in turn implemented in an object oriented way such that functionality to be written can be easily modified or wrapped.

10. DISADVANTAGE OF ACTIVE DATABASE Insufficient methodological support in design and analysis. Lack of standardization. Missing development and administration tools for triggers. Weak performance. Lack of support for application development.

11. ADVANTAGE OF MAIN MEMORY DATABASE It has direct access to data and uses shared memory architecture. It is handwritten using atomic instructions. It has fixed and variable size allocators. Code segments which are performance critical are tightly coupled.

12. DISADVANTAGES OF MAIN MEMORY DATABASE They may not be cost effective. There may be risk of data loss. There is a limit in the database.

13. APPLICATIONS OF ACTIVE DATABASE D ata monitoring activities such as Telecommunications Network Management, Program trading, Medical and Financial Decision Support etc . Production control activities such as power plants. Maintenance task activities e.g. inventory control systems. Air traffic control, Computer interrogated manufacturing, Statistic gathering and authorization tools etc.  

14. APPLICATIONS OF MAIN MEMORY DATABASE Used in real time embedded systems. Manage the music databases in a MP3 player. P rogramming data in set-top boxes, arithmetic trading and other financial applications . E- Commerce and Social Networking sites.

15. CURRENT RESEARCH OF ACTIVE DATABASES A new condition called Petri Nets is proposed to approach the model and rules of ECA. It can integrate the rules and is also independent of the original database. A study for concurrency control is going on for real time active database systems where they are exploring the dynamics of transaction processing for real time active databases. A research for real time event control in active databases is being carried out.

16. CURRENT RESEARCH OF MAIN MEMORY DATABASES A research for the implementation techniques for Main Memory Databases is being carried out where evaluation of AVL vs B+ tree access methods for the said database is done.

17. FUTURE WORK ON ACTIVE DATABASE Research for new ECA rules. Controlling data concurrency in real time.

18. FUTURE WORK ON MAIN MEMORY DATABASE Research for Disaster Recovery of the database. Extension of the model for unstructured data structures. Life cycle based data management is based on the semantics of different applications it is possible to specify if a single record is ever modifies again or remains read-only and thus allows different strategies for compression and partitioning.

19. CONCLUSION Active databases are those types of databases that have the mechanism to automatically respond to events in the system where as Main memory databases are the databases that reside permanently in main memory. Active database includes an event driven architecture. Main memory database completely relies on main memory for computer data storage. Most modern relational databases include active database in the form of database triggers. Main memory databases are quite faster .

20. REFERRENCE   https://en.wikipedia.org/wiki/Active_database https://en.wikipedia.org/wiki/In-memory_database www.slideshare.net Database System Concepts by Silberschatz−Korth−Sudarshan

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