In the 24/7 working environment, any organization requires database available all time. In business world, there are three type of users (Top Management(C.E.O, Board of Directors etc), Technical user(DBA, Developers etc.)/Non -Technical user(Hr , C.A, Market department etc.), End Users(Customers) )who interact with database any organization according to their roles and privileges. N number of activity done by them get stores into the database. Day to day life Retrieval, manipulation, an update occurs in so many times. Due to maintaining the data as original we need backup every time. We can find different methods and strategies are available in different RDBMS in the technical market. Oracle has different methods and strategies to get backup as compared to MS SQL Server. In this article, we are going to know about backups and its type Oracle database provider to maintain the database.
What is Backup?
A backup is a copy of one or more files created as an alternate in case the original data is lost or becomes unusable.Backups can be divided into physical backups and logical backups.
Why do we need Backup of a database?
- Backups are a way to protect the investment in data. By having several copies of the data, it does not matter as much if one is destroyed (the cost is only that of the restoration of the lost data from the backup).
- Data is valuable. It will cost you time and effort re-create it, and that costs money or at least personal grief and tears; sometimes it can’t even be re-created, e.g., if it is the results of some experiments. Since it is an investment, you should protect it and take steps to avoid losing it.
- Data loss can happen in many ways, the most common causes are a physical failure of your PC, accidental error, theft or disasters like fire, flood and dropped coffee mugs! It is also common for data to be saved to just one place, like ‘My Documents’ on your PC’s hard drive. Which means that if this data were to be accidentally changed or deleted it would take considerable time and expense to restore it.
- There are basically four reasons why you might lose data: hardware failures, software bugs, human action, or natural disasters. Although modern hardware tends to be quite reliable, it can still break seemingly spontaneously.
Logical Backup: – A logical backup copies data, but not physical files, from one location to another. It extracts every record in the database and stores it in a different format.A logical export backup generates necessary Structured Query Language (SQL) statements to obtain all table data that is written to a binary file. A logical export backup does not contain database instance-related information, such as the physical disk location, so we can restore the same data on another database machine.Logical backup means backing up the database objects like tables, views, indexes…etc using the EXPORT utility given by Oracle. The objects exported in this way can be imported into either same database or into any other database. The backed-up copy of the information is stored in a dump file, and this file can be read using another utility called IMPORT. The logical backup can be made also through a remote process.
Physical Backup: – A backup is a copy of data from your database that can be used to reconstruct that data. Physical Files, such as text files, are stored as a single document on your hard drive. Although databases consist of many complex elements, these are usually aggregated into simple files on your server’s hard drive. These files can easily be backed up just like any other files on your system.
This diagram gives the glimpses of Oracle’s Backup.
Can you please explain how we can take incremental backups using data pump ?
Our intention was to talk about scn based expdp for consistency.
There is a parameter in traditional Exp utility.
Specifies the type of incremental Export. The options are COMPLETE, CUMULATIVE, and INCREMENTAL