Components of Oracle

When we install oracle then some of the components are installed. The components installed are:

1. Database
2. Instance
3. Client

Don't matter which version and which edition we install, these components are installed in our system. If we install oracle 10g express edition then these three versions are installed. If we install oracle 11g enterprise edition then also these three components are installed. Now let's talk about all components in details:

Database

After installing oracle one database is created by default by installer. If we are installing express editions then "XE" database is created. In the case of enterprise edition "ORCL" database is created. 
Database is divided in two part.

• Logical database
• Physical database

When we install data in database the first data stored in physical database that is data files. The extension of data file is .DBF. When we request for a data or write a query then it will shown in tables that is called logical database. We can also say that, in oracle data are logically stored in table and physically stored in data files.

 

 

Instance

Instance is the way to access database. So, always database is associated with instance. We cant access database without instance. The place where these two components are created is called oracle server. Databases are created in hard disk and the instance is created in RAM.

Client

Using oracle client user :

• can connect to oracle server.
• submit request to oracle server.
• receive response from oracle server.

Various clients are available in marker for communication to oracle server. Some of them are:

• Sql*plus (completely CUI based)
• Toad (GUI)
• Sql developer (GUI)
• Pl/Sql developer (GUI)