Reasons for using ORDBMS over RDBMS

Why do we need ORDBMS / Reasons for using ORDBMS / Advantages of ORDBMS

 

Reasons for having ORDBMSs over conventional RDBMSs

• Storage requirements of newer applications - Conventional RDBMSs cannot handle the data like engineering designs, scientific experiments, GIS, and multimedia data.

• Handling of data stored for newer applications – retrieve and manipulate data stored for newer applications like other data with RDBMS functionalities.

• Ability to define user defined data types – to handle new type of data as and when required.

• Reusability nature of objects – One of the main features of using objects, and methods.

• Database extensibility – easy addition of data types and operations

And finally, the inability of RDBMS to handle the above said things.

Object-based Database Systems - Overview

Object Based Database Systems Overview

It is a type of Database Management System where the information that is stored and manipulated is all in the form of objects. Through Object based database systems, we are really incorporating the features of Object Oriented Programming like objects, classes, and inheritance.

Object Relational DBMS (ORDBMS)

The conventional RDBMS is extended with new functionalities of storing and manipulating data in the form of objects. We mention that type RDBMS as ORDBMS.

The RDBMS combines its conventional capabilities such as,

• Secondary storage management
• Schema management
• Concurrency control
• Transaction management, recovery
• Query processing
• Access authorization and control, safety, security

with the capabilities of object oriented programming such as,

• Complex objects
• Object identities
• User-defined types (ADTs)
• Encapsulation
• Type/class hierarchy with inheritance
• Overloading, overriding, polymorphism

Figure 1 - ORDBMS = RDBMS + OOP

4 necessary conditions for occurrence of deadlock

Four necessary conditions for occurrence of deadlock in databases / Four necessary conditions for deadlock to occur / Necessary and sufficient conditions for deadlock / List and discuss four conditions for deadlock / Necessary conditions that ensures a deadlock occurrence state

 

Necessary conditions for deadlock to occur in database

A deadlock can arise if the following 4 conditions hold simultaneously in a system;

• Mutual exclusion: At least one resource is held in a non-sharable mode. For example, among transactions if there is any Exclusive lock (Write lock) request, that data item cannot be shared with others.

• Hold and wait: There is a transaction which acquired and held lock on a data item, and waits for other data item.

• No preemption: A situation where a transaction releases the locks on data items which it holds only after the successful completion of the transaction. Not on voluntarily.

• Circular wait: A situation where a transaction say T1 is waiting for another transaction T2 to release lock on some data items, in turn T2 is waiting for another transaction T3 to release lock, and so on.

During transaction processing, if all the said conditions are held then there occurred a deadlock.

Go to Deadlock Handling Techniques in Database page
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List of necessary conditions for deadlock to happen in database

Strengths and weaknesses of trigger mechanisms

Strengths and Weaknesses of Triggers / Advantages and Disadvantages of using Triggers / Merits and Demerits of Trigger mechanisms

 

Strengths and Weaknesses of Triggers / Trigger mechanisms

Strengths

• Used for enforcing referential integrity.
• Easy to implement business rules through triggers.
• Event logging is easier.
• It can control transactions hence lead to safer transactions.
• Consistency is maintained.
• Efficiency in performing transactions.
• Cascading referential integrity.
• Implicitly called for actions during database changes. Very much helpful in a case where many changes need to be done on different tables for a single action.

Weaknesses

• Triggers should be written with extra care. Trigger error may lead to failure of insert, delete, or update operations at runtime.
• Excessive use of triggers can result in complex interdependencies. For example, cascading triggers can induce chain of actions.
• Increased complexity.
• May decrease the performance of the database.
• Every time a trigger is fired, its code must be recompiled.
• Database triggers can be accidentally disabled or dropped by a person with sufficient privilege.
• The hidden nature of triggers is another important weakness.