The main features of the area are as follows:
Context:
Unlike a relational database, which usually works with SQL, an object , oriented database works in the context a regular programming language such as C++. C or Java. Furthermore, an object oriented database may be host-specific, or it may be able to read the same database from multiple kinds of host, such as a SPARC server under Solaris 8 and a PC under Linux. Some object oriented database servers can support heterogeneous clients, so that the SPARC system and a PC and a Macintosh, e.g., might all be accessing the same database.
Persistence:
With an object oriented database, the software calls a database function to load the illustration, but objects are not created in memory until they are needed; Instead, they are stored in the database, and only references are loaded into memory.
When an object is changed, the database silently writes the changes to the database, keeping the in-database version up-to-date at all times. When the user presses "save", all the application does is to commit the current transaction; since the database is already up-to-date, this is generally very fast. The code no longer needs to be able to read or write the proprietary save file format, and may well also run faster.
Accessing Data:
Most of the time, an application using an object oriented database access data by navigation. For example, in C or C++ data is accessed by pointers and in Java by references.
Binding to Objects:
Objects in Object-oriented database are bind as string or integers using pointers. This helps in retrieving those objects later.
Saving Objects:
Most object-oriented databases save objects automatically when there use is finished. It is needed to delete unwanted objects explicitly.
Queries:
An object-oriented database performs well if lots of pointer- style navigations are used and relatively few queries. There is no standard query language for an object.-oriented database. Object Database Management Group (ODMG, an industry consortium) has defined the Object Query Language (OQL).
Indexing:
Just as with a relational database, an object oriented database can often create an index so that accessing a particular field can be very Fast.
Transactions:
As with a relational database, a transaction is a sequence of database operations that must either all complete or all fail. If any of them fails, or if the program calls an abort method or raises exception, the entire transaction is aborted. Only when the transaction finishes can other database clients see any of the changes, Some databases may lock other threads trying to access data that is being changed in another transaction; this means that there may be a possibility for deadlock, where multiple threads (or programs) are all waiting for each other. The ODMG specification does not allow nested transactions, although some vendors support them; again, this can increase the chances of deadlock, but it can also simplify programming and design.
Distributed Objects:
Some object-oriented databases permit objects to migrate from one database server to another. They might move to the server that requested them most recently.
SIMILAR KEYWORDS:
Characteristics of the object-oriented database management system
Main features of an object-oriented database management system
