Logfile Switch command in Oracle
Oracle has two ways to force a logfile switch.
ALTER SYSTEM SWITCH LOGFILE;
ALTER SYSTEM ARCHIVE LOG CURRENT;
Both will force a log switch log and move to another available redo log file(having status inactive).
Both commands work differently:
1. ALTER SYSTEM SWITCH LOGFILE
- It is fast return control to user because it does not wait for the archiver process to complete writing the online redo log to archive log file.
- It start writing to the new redo log file by issue checkpoint, then in back-group it tell archiver process to copy the redo to archive file.
- In RAC environment it worked only on local node.
- It is asynchronous process it only invoke the background process and control return to user.
- It use current thread for archives only.
2. ALTER SYSTEM ARCHIVE LOG CURRENT
- It is paused because it waits for the archiver process to complete its writing process of online redo log to archiver file.
- In RAC environment it switch the logs on all RAC nodes.(recommended in RAC Environment).
- It is synchronous because command waits until the online redo log has completed the writing of the redo log file to the file system.
- In RMAN backup it is the trusted command.
- You can specify the thread to archive in this command.