What is online redo log files in Oracle?
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What is online redo log files in Oracle?
Every Oracle database has a set of two or more online redo log files. The set of online redo log files is collectively known as the redo log for the database. A redo log is made up of redo entries, which are also called redo records. The online redo log stores a copy of the changes made to data.
What are the redo log files that are no longer required?
Redo log files that are no longer required for instance recovery are called inactive redo log files. If you have enabled archiving (the database is in ARCHIVELOG mode), then the database cannot reuse or overwrite an active online log file until one of the archiver background processes (ARCn) has archived its contents.
How do I create an online redo log in Oracle?
To create a new group of online redo log files, use the SQL statement ALTER DATABASE with the ADD LOGFILE parameter. The following statement adds a new group of redo logs to the database: ALTER DATABASE ADD LOGFILE (‘/oracle/dbs/log1c. rdo’, ‘/oracle/dbs/log2c.
How do you increase the size of the online redo log?
To increase redo log size from 50MB to 1GB, we take the following steps to reach the goal.
- Check Current Redo Logs.
- Add 3 Groups with New Size (1GB)
- Switch Logfile to New Groups.
- Force a CheckPoint.
- Drop Group 1, 2, 3.
- Remove Redo Log Files.
- Add Group 1, 2, 3 with New Size (1GB)
- Switch Logfile Several Times.
What is online and offline redo log files in Oracle?
The online redo log file actively being written by LGWR is called the current online redo log file. Online redo log files that are required for instance recovery are called active online redo log files. Online redo log files that are not required for instance recovery are called inactive.
How do you Multiplex redo log files?
To multiplex your redo log, you must add members to each redo log group. It is not required that redo log groups be symmetrical, but Oracle recommends that your groups all have the same number of members. A database must have a minimum of two redo log groups.
How do I create an online redo log file group and members?
To create a new group of redo log files, use the SQL statement ALTER DATABASE with the ADD LOGFILE clause. The following statement adds a new group of redo logs to the database: ALTER DATABASE ADD LOGFILE (‘/oracle/dbs/log1c. rdo’, ‘/oracle/dbs/log2c.
How do I change the redo log size in Oracle 11g?
Instructions
- Stop eHealth.
- Start sqlplus using the eHealth adminstrative account.
- To find the location of your current redo logs, run:
- There are four redo log groups; make sure that group 1 is not listed as CURRENT.
- Drop group 1.
- Create a new group with with a larger size.
- Make the new group 1 CURRENT.
Can I have redo log groups with different size?
All members of the same multiplexed redo log group must be the same size. Members of different groups can have different sizes. However, there is no advantage in varying file size between groups.
