Object Oriented Databases

Object Oriented Databases
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Object-oriented databases are also called object data management systems. Objects stored in Object-Oriented Programming Languages (such as Smalltalk, C ++, and java) not only store integers, strings, and real numbers like relational databases. Objects generally consist of the following parts:

-- Attribute: quantifies the features of an object. These quantities may be simple integers, strings, or real numbers, or complex objects.
-- Method: A method is also called a process or function. A method specifies the behavior of an object.

Therefore, an object contains executable code and data. Of course, the object also has other features, such as whether a method or data can be obtained outside the object, but for the sake of simplicity and ease of understanding of our article, it is applied to the object-oriented database, we will not consider this in this article. Another thing to mention is "class ". Classes are used in Object-Oriented Programming to specify the methods and data contained in an object. Class is like an object template. The class does not contain methods and data, but specifies the methods and data to be included in the object. Classes are used during object creation. In the object-oriented database, classes are used to create parts of objects that are not stored in the database (such as object methods ).

Comparison with relational databases

Relational databases store data in two-dimensional tables that contain rows and columns. Since relational database tables are "formatted", there will not be too many data duplicates. All columns depend on the primary key (the unique value in the column) to identify this column. You can use a specific value of a specific column to obtain or change the value of a row.
To put objects in a relational table, simple data such as strings, integers, and real numbers must be used to describe the class. For example, to describe an airplane, the airplane wing will use an independent table to describe its size and other characteristics. The fuselage will be described in another table, and the propeller and tires will also be described in a separate table, and so on.
Dividing complex information into simple information requires labor, and code must be completed here.

Object Persistence

In traditional databases, the data operated in the program is temporary, and the data stored in the database is persistent (stored on permanent storage devices ). In object-oriented databases, programs can operate on temporary data and persistent data.

When to use Object-oriented Data

If the procedures manipulate very complex data or the relative relationship between the data is more complex, use the object-oriented database, especially the many-to-many object relationship. If there are few links to data or a large amount of data, it is best not to use an object-oriented database.

Object-Oriented Database applies:

-- Computer Aided Modelling Program (Computer Aided Software Engineering, Computer Aided Design, computer aided manufacturing)
-- Multimedia Program
-- Project engineering software that changes over time
-- Commercial Software

Advantages of Object-Oriented Database

-- Objects do not need to be packed or unpacked, saving programming and execution time.
-- Reduce Paging
-- Easy navigation
-- Better concurrency control-the object hierarchy may be locked.
-- Data models are based on the real world.
-- Works well in a distributed architecture.
-- If the program is also object-oriented, the amount of code can be reduced.

Disadvantages of Object-Oriented Database

-- If the relationship between data and data is relatively simple, the object-oriented database is less efficient.
-- Relational Tables are easier to understand.
-- Later binding may slow down access.
-- Relational databases have more tools.
-- Relational database standards are more stable.
-- The services and support of RDBMS are more stable and do not need to be changed.

ODBMS Standard

-- Object Data Management Group)
-- Object Database Standard ODM6.2.0 (Object Database Standard ODM6.2.0)
-- Object Query Language)
-- The object query language supports SQL92 (OQL support of SQL92)

How to store data

Different database providers use two basic methods to store data.
-- Each object contains a unique ID and is defined as a subclass of a basic class. It is determined by an inherited method.
-- Use virtual memory ing to store and manage objects.
Data transmission is based on objects or pages (usually 4 K.

---- Article: http://www.comptechdoc.org/ind... html. If the translation is incorrect, correct it. This article is also published in http://ood.tson.com/article/9, welcome to comment.

Computer vocabulary

One of the four-level computer examination terms:

Access, and access
Adjacency list method
Adjacency matrix method
Algorithm
Array
Asynchronous transfer mode asynchronous transmission mode
B. real programs kernels core program
B. toy benchmark synthetic benchmark simple benchmark program composite benchmark program
Bandwidth
Benchmark benchmarking Program
Best-fit algorithm optimal adaptive algorithm
BFS (breadth first search) breadth-first search
Binary
Binary relation
Binary tree
Bit series
Black-box white-box black box white box
Block miss block failure
Blocked blocking (the waiting status is also called blocking or blocking status)
Boundary
Bridge
Bubble sort bubble Sorting
Candidate key (secondary key)
Capacity
Cartesian product
CASE (com.. aided sof .. engineering) Computer aided Software engineering
CCP (communication control processor) communication control processor
Cell
Characteristic features
Circuit switching line switching
Circular wait loop wait
CISC (complex instruction set computer) complex instruction set computer
Class
Client/Server
Clock cycle/clock rate clock cycle/clock frequency
Coaxial cable
Cohesion/coupling
Coincidental logical procedural functional accidental cohesion logical cohesion process cohesion function cohesion
Communication
Complement number complement
Constrain Constraints
Contain inclusion
Correspond (corresponding) is consistent)
CPETT computer performance evaluation tools and technology
Number of cycles required for each CPI command
CSMA/CD Multi-Channel Access to carrier listeners with Conflict Detection
Cursor
Cyclic redundancy check cyclic redundancy Test
Database: integrity consistency re story integrity consistency recoverability
Database: security efficiency database design goals: security efficiency
Deadlock: mutual exclusion deadlock condition: mutex
Deadlock: circular wait no preemption deadlock condition: loop wait has no priority
Decimal
Demo-decision judgment
Decomposition
Definition
Definition phase definition ...... remaining full text>

Computer Professional English help

NOTES [1] ARPA is short for Advanced Research Projects Agency, which refers to (US) Advanced Research Institute. [2] TCP/IP internet adopts the TCP/IP protocol. [3] terminals refers to various terminals connected to the Internet. [4] usually is followed by slang. [5] Two parallel components connected by and. The subject is Search engines. Search criteria (keywords ). [6] the reasons that lead to the adverbial clause. [7] Here, TCP/IP refers to an email that is supported by the TCP/IP protocol. Relay indicates forwarding. In the [8] clause, connections indicates that both parties establish a connection before communication. them also indicates connections. [9] a long sentence composed of multiple parallel objects. [10] in a sentence, it is the first object, and appear is the object complement. The clause derived from that is the real object. In this clause, by sending... and displaying... are the inactive nouns. KEYWORDS Internet ARPAnet ARPA computer network, Apache packet-switching network group exchange network, packet exchange network interoperability WWW (world wide web) world wide web, hypertext client browser download HTTP (hypertext transfer protocol) Hypertext transfer protocol URL (uniform resource locator) unified resource positioning address: search engine search criteria search Condition Web page GUI (graphical user interface) graphical user interface IE (Internet Explorer) (Microsoft) browser software Mosaic American Computer Security Association (NCSA) Public WWW browser Navigator (Wangjing Company) browser electronic mail email SMTP (Simple Mail Transfer Protocol) simple Mail Transfer Protocol POP (Post Office Protocol) Post Office Protocol FTP (File Transfer Protocol) File Transfer Protocol Telnet (Telecommunication network) Remote Communication network TCP/IP (Transmission Control Protocol/Internet Protocol) transmission Control Protocol/Internet Protocol access, access to adjacency list method neighbor table notation adjacency matrix method neighbor matrix notation algorithm array ATM (asynchronous transfer mode) asynchronous transmission mode B .. real programs kernels core program B .. toy benchmark synthetic benchmark simple benchmark program composite benchmark program bandwidth benchmark benchmarking program best-fit algorithm best adaptive algorithm BFS (breadth first search) breadth-first search binary relation ...... remaining full text>