What is the purpose of Redo Log files?

What is the purpose of Redo Log files?
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1 Answer

Answer :

Before Oracle changes data in a datafile it writes these changes to the redo log.
If something happens to one of the datafiles, a backed up datafile can be restored and the redo, that was written  since, replied, which brings the datafile to the state it had before it became unavailable.
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Related questions

What is the use of redo log information?

Description : What is the use of redo log information?

Last Answer : The information in a redo log file is used only to recover the database from a system or media failure prevents database data from being written to a database's data files.

What is the function of redo log?

Description : What is the function of redo log?

Last Answer : The primary function of the redo log is to record all changes made to data.

What is a redo log?

Description : What is a redo log?

Last Answer : The set of redo log files for a database is collectively known as the database redo log.

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Description : What is Archived Redo Log ?

Last Answer : Archived Redo Log consists of Redo Log files that have archived before being reused.

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Description : What is On-line Redo Log?

Last Answer : The On-line Redo Log is a set of tow or more on-line redo files that record all committed changes made to the database. Whenever a transaction is committed, the corresponding redo entries temporarily ... file by the background process LGWR. The on-line redo log files are used in cyclical fashion.

What is meant by redo log buffer ?

Description : What is meant by redo log buffer ?

Last Answer : Changes made to entries are written to the on-line redo log files. So that they can be used in roll forward operations during database recoveries. Before writing them into the redo log files ... buffers in SGA and LGWR will write into files frequently. LOG_BUFFER parameter will decide the size.

What is meant by Redo Log file mirroring ? How it can be achieved?

Description : What is meant by Redo Log file mirroring ? How it can be achieved?

Last Answer : Process of having a copy of redo log files is called mirroring. This can be achieved by creating group of log files together, so that LGWR will automatically writes them to all the members ... . If any one group fails then database automatically switch over to next group. It degrades performance.

What is a Redo Log ?

Description : What is a Redo Log ?

Last Answer : The set of Redo Log files YSDATE,UID,USER or USERENV SQL functions,or the pseudo columns LEVEL or ROWNUM.

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Description : What is Mirrored on-line Redo Log ?

Last Answer : A mirrored on-line redo log consists of copies of on-line redo log files physically located on separate disks, changes made to one member of the group are made to all members.

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Description : How does one backup archived log files? (for DBA

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Last Answer : Redo logs are logical and physical structures that are designed to hold all the changes made to a database and are intended to aid in the recovery of a database.

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Description : What is a Redo Log?

Last Answer : The set of Redo Log files YSDATE,UID,USER or USERENV SQL functions, or the pseudo columns LEVEL or ROWNUM.

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Last Answer : A mirrored on-line redo log consists of copies of on-line redo log files physically located on separate disks, changes made to one member of the group are made to all members.

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Last Answer : Archived Redo Log consists of Redo Log files that have archived before being reused.

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Description : What is On-line Redo Log?

Last Answer : The On-line Redo Log is a set of tow or more on-line redo files that record all committed changes made to the database. Whenever a transaction is committed, the corresponding redo entries temporarily stores in redo log buffers of the SGA are written to an on-line redo log file by the background

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