Oracle External Table

Suppose we have a text file named “emp.data”. This text files contains employees data in following format,

1, Michle , clerk
2, king , manager
3, joe , clerk

What if we want to use this data in SQL query? Remember we do not want to import this data in oracle database but we want to reference this data from its physical location. To achieve this oracle database has provided a feature called External Tables. Using this feature, we can register “emp.dat” file in oracle database as external table. Continue reading “Oracle External Table”

Archivelog mode concepts | Oracle Hot backup and cold backup

We take complete physical backup of database by copying physical database files including datafiles, control files, password file and parameter file. Backup can be online backup or offline backup. In online backup, our database is in open stage and datafiles have different SCN. Continue reading “Archivelog mode concepts | Oracle Hot backup and cold backup”

Undo Management and Undo Tablespace | Undo Retention

When a query tries to modify database, original data entries are kept in separate location and then changes are applied to datafiles. The data kept in separate location is called Undo data. Undo data is used to maintain data integrity and data consistency.Oracle uses Undo data in following situations Continue reading “Undo Management and Undo Tablespace | Undo Retention”

Introduction to Oracle Backup and Recovery | Oracle Flashback Features

Oracle has provided powerful mechanism to protect database in situation of data loss. This mechanism includes a range of methods to Backup and Recover your data. First step is to backup you data and second step is to recover required data. Broadly speaking, oracle supports two types of backups, Logical Backup and Physical database backups.

Continue reading “Introduction to Oracle Backup and Recovery | Oracle Flashback Features”

Configuration of Oracle Shared Server

This article explains configuration of oracle Database 10g as shared server. Before reading this article you must have concept of Oracle shared server and dedicated server architecture. Visit following link to revive shared server and dedicated server architecture.

http://exploreoracle.com/2009/07/17/oracle-shared-server-and-oracle-dedicated-server-architecture/

Configuration of shared server involves only few steps. Oracle database 10g has pre-configured setting to enable shared server. Shared server can be configured by setting values for few initialization parameters at run time. These parameters can also be initialized in initialization parameter file. Following section discusses these parameters in detail. Continue reading “Configuration of Oracle Shared Server”