could anyone give me a summarilized explanation:
during the recovery, what's kind condition needs to resetlogs and when needs noresetlogs.
all input will be appreciated
When you do incomplete recovery, then you must open the database with resetlogs. This will create new redo log files.
what if my old log files are good, do I still need to use resetlog
When recovering using RECOVER DATABASE USING BACKUP CONTROLFILE and then you will have to specify resetlogs inorder to open the database.
But when you are using RECOVER DATABASE, then you can open the database with NORESETLOGS option.
However in both the cases, your purpose is served to recover the database. Only the problem with RESETLOGS will be, the backup DB will become obsolete.
I hope this clears it!
So, the bottom line is take a complete backup of all your datafiles,control files,redolog files/init and config.ora files before using resetlogs option.
You reset the logs, so that they do not contain any transactions later than recovery time.
I thought resetlogs when:
1. recreate redo log due to lose all redo log files
2. recreate control files
3. any file/tablespace SCN out of sync (ex. system tablespace) or currupted
all other case can use noresetlog
basically when you lose all redo logs and you recover the database you are perfoming an incomplete recovery therefore you have to reset the logs.
Incomplete recovery means not recovering until point of failure.
Recreating the control file doesnt necessary means you have to reset the logs since it can be a complte recovery.
RECOVER DATABASE USING BACKUP CONTROLFILE doesnt force a resetlogs neither as long as when you recreate the control file you specify CREATE CONTROLFILE REUSE DATABASE XXXXX NORESETLOGS, if RESETLOGS were used then you will be forced to reset the logs.
Finally when you ever have to use resetlogs option then it basically means you have performed an imcomplete recovery.
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