Data recovery from Oracle databases can be broadly categorized in three sections which are data file media recovery, complete and point in time recovery and crash recovery. Fundamental type is the media recovery for deleted or corrupt database objects and files. Complete recovery is associated with restoration of all the objects within the database until the last successful backup. Point in time recovery can be performed up to some time frame based on the user input. Crash recovery is normally performed after the database has suffered any damages or it has completely crashed. Every process has its own unique features, benefits and limitations. Professional database experts will be able to give you accurate services based on your need.
We have developed a system of infrastructure wherein the team of Oracle database experts works with your team members in restoring the databases from backup servers, perform periodic backup and execute other tasks related to complete database recovery and backup management.
By default the, recovered objects will overwrite the existing records, indexes, primary keys, foreign keys and other Meta data related to tables, queries and other objects in the database when data is recovered from a backup file. If you wish to avoid overwriting, you need to uncheck the box in the recovery dialog box in the recovery wizard.
RMAN is one of the client utilities in Oracle platform used for backup and recovery operations. It can support SQL+ commands apart from offering its own set of commands and stored procedures. When you go for a stored procedure for recovery of database files you get many benefits.
- Reuse: – A specific stored procedure can be used n-number of times, since it is more like using a written program repeatedly. You will be able to edit the stored procedure many times, add commands, edit the existing commands and delete the previously input commands.
- Speed: – Stored procedures are stored in the server end of the database and they run in the server space, returning only the result sets to the client end. When you compare this with the execution of SQL+ commands from the client end time consumed is about 10% and the reliability of execution is 100%. Most of the commands can be run without the fear of ending up with incomplete transactions.
Customized queries are another feature of Oracle database systems. These queries can be stored in event based commands like triggers. They may be single line commands or multiline commands like the stored procedures. They are normally associated with user actions like single click, double click or system driven event like completion of a process. Once the triggers are linked to these events, they get executed automatically without the need of user intervention. For example you will be able to initiate a backup process at 12:00 AM by connecting the trigger based backup commands to the system clock in the server database. The commands start getting executed whenever the system clock strikes 12:00 AM. This is a sort of automated command execution.
The Oracle database system offers three types of queries, namely data definition query, data manipulation query and data management query. You will be able to know the exact status of the backup and recovered database files with the data management queries like the SELECT statement.
Client utilities offered by Oracle RMAN can be use for fixing the database restore points. They can be invoked with the help of SQL+ commands. There are three types of restore points like the Normal restore point and assured restore point. Normal restore points can be created at any point of time by the users and they are used for restoring database files. You will be able to specify any future date and time at which the restoration process has to be initiated. In such cases you need to specify the particular path from which the system can restore the files. Since you will be running this command as a database administrator from the server end, you don’t need to specify the target path unless it is absolutely essential. Here also you can make use of RMAN commands and stored procedures which are easy to correlate with RMAN commands. In case you feel that the task of executing RMAN commands tough, you can always depend on professional database technicians in order to create and execute the RMAN commands from the scratch. The technician will be able to work with RMAN commands as well as SQL+ commands from the RMAN client application which communicates with the Oracle server processes which are directed towards the target databases. The other way in which RMAN can be used is through the Enterprise manager utility available in the Oracle system. This is a GUI through which the system offers customized data backup and recovery services across the complete network.
When the data storage media in the server fails, you need to call for the immediate help of hardware recovery expert for restoring the storage media before executing any other command. This can be done effectively with the help of software and hardware tools provided by the OEM of the disk drive.
You need to make sure that you always use the software utilities offered by OEM for setting right any logical errors in the server disk space. This is to ensure that the errors are completely eliminated before you can plan to recover the deleted oracle database system back into its original place. In cases of physical damages that cannot be restored, it is better to replace the failed disk with a new one and recover the backup Oracle databases into that disk, after reinstalling the server OS and reinstating the network connections.
You will be able to utilize the best of software disk utilities if you choose to install the Oracle database systems onto Windows 2008 sever or the later versions. If the server has a strong active directory system and service packs installed, it becomes more affordable to install the Oracle database systems into such environment.