Oracle - SPLessons
boy2 Chapter 23

Oracle Data Files

Oracle - SPLessons

Oracle Data Files

shape Description

Oracle Data Files contain one or more physical information files. The information files subsist all the database information in the Oracle Data Files. The information of legitimate database design are indexes and tables, is naturally put away in the Oracle Data Files dispensed for a database. The qualities of Oracle Data Files are:

  • A dataset can be connected to a single database.
  • Oracle Data Files contain qualities collections for consequently extend when the database come up short of space.
  • One or more data files structure a coherent unit of database stockpiling called a table space.


shape Conceptual
figure

Information in a dataset is perceived, as required, amid typical database application and put away in the collection store of Oracle. For instance, accept that a client needs to get to some information in a table of a database. In the way that the  data is not same as the way that the data contained in the  database, then it is used from the suitable data files and put away in consciousness. The database operation is running for multiple process with shared server, in which the server database code is running. The Oracle database server code running for all the server can be served for multiple clients forms. All the associated client contain a different client process, and Oracle Database process contain several background process.

Altered  information is doesn’t necessary to keep inside the data record. To decrease the measure of plate access and to expand execution, information is pooled in memory and kept in touch with the proper data set at the same time, as dictated by the database author in process foundation process.

shape Examples

By viewing the below example, the concept of data files has been explained with joins.

sql> select * from emp17;
+--------+--------+--------+
| emp_id | ename  | deptno |
+--------+--------+--------+
|   1001 | jhon   |     10 |
|   1002 | shah   |     20 |
|   1003 | maddi  |     10 |
|   1004 | maddie |     20 |
+--------+--------+--------+
4 rows in set (0.00 sec)
sql> select * from dept13;
+--------+-----------+-----------+
| deptno | dept_name | dept_city |
+--------+-----------+-----------+
|     10 | leo       | texas     |
|     20 | vin       | newyork   |
+--------+-----------+-----------+
2 rows in set (0.00 sec)
sql> select * from emp17,dept13;
+--------+--------+--------+--------+-----------+-----------+
| emp_id | ename  | deptno | deptno | dept_name | dept_city |
+--------+--------+--------+--------+-----------+-----------+
|   1001 | jhon   |     10 |     10 | leo       | texas     |
|   1001 | jhon   |     10 |     20 | vin       | newyork   |
|   1002 | shah   |     20 |     10 | leo       | texas     |
|   1002 | shah   |     20 |     20 | vin       | newyork   |
|   1003 | maddi  |     10 |     10 | leo       | texas     |
|   1003 | maddi  |     10 |     20 | vin       | newyork   |
|   1004 | maddie |     20 |     10 | leo       | texas     |
|   1004 | maddie |     20 |     20 | vin       | newyork   |
+--------+--------+--------+--------+-----------+-----------+
8 rows in set (0.00 sec)

In the above example, the Cartesian join combines both emp17 table and dept13 table and update the values to all the fields based on depno, so that each and every employee will have completed details with duplicate values.

Summary

shape Key Points

  • Oracle Data Files – It contain multiple physical information files that are related to data files.