Rolling back and Rolling forward are the two most common operations performed during instance recovery.
Have a look how they are different in nature.However first rolling forward occurs then rolling back during crash recovery:
Rolling back: During this operation, uncommitted changes that were added to the datafiles during the rollforward operation are rolled back. Oracle does this by using the undo tablespace contents to return uncommitted changes to their original states. At the end of the rollback stage, only committed data at the time of the instance failure is retained in the datafiles.
Have a look how they are different in nature.However first rolling forward occurs then rolling back during crash recovery:
Rolling forward: During this operation, the Oracle server will update all datafiles with the information from the redo log files. The online redo log files are always written to before the data is recorded in the datafiles. Thus, an instance recovery may usually leave the online log files “ahead” of the datafiles.
Rolling back: During this operation, uncommitted changes that were added to the datafiles during the rollforward operation are rolled back. Oracle does this by using the undo tablespace contents to return uncommitted changes to their original states. At the end of the rollback stage, only committed data at the time of the instance failure is retained in the datafiles.
Enjoy:-)
3 comments:
new orleans saints jerseys
coach outlet
jordan 4
polo ralph lauren
rolex replica watches
michael kors uk
adidas nmd
nike roshe
gucci sito ufficiale
michael kors bags
birkin bag
kd 11
yeezy boost
pure boost
fila
michael kors handbags
reebok shoes
off white hoodie
fitflops sale clearance
yeezy boost 350 v2
replica bags philippines gucci replica handbags v1a45y6a30 replica bags online shopping advice k2l29z7y65 gucci replica replica bags cheap replica bags china visit here x1m65f0n11 replica bags joy
Post a Comment