Transaction recovery use undo tablespace
frank, October 09, 2021 - 2:11 pm UTC
Hey tom from what i know the transaction recovery(which rollback the uncomitted transaction) use the undo information stored in undo tbs not in redo log
Is this concept wrong?
October 11, 2021 - 10:53 am UTC
Yes but we need to get that information *back* into the undo tablespace after a power outage, so that we can then *use* it to undo any uncomitted transactions.
We use the redo to bring the undo tablespace back to a correct state.
samchj, December 09, 2021 - 3:32 am UTC
Hi Tom, is that feature for 19c or exactly exist at 11g\12c?
when I backup a database from standby, and try to recover using backup control file and got oral-660[3020] /ora-10567/ora10561, I just thought caused by this issue. I used oracle 11.2.0.4
December 10, 2021 - 3:09 am UTC
The logging on undo blocks has existed since Oracle has existed (well, probably back to Oracle 3 or 4)
history essay
bore, December 10, 2021 - 6:44 am UTC
Term Undo was introduced in 9i. Old Rollback segments began to be called manual undo management. New mechanism is called automatic undo management.
In the manual undo, the rollback segments are explicitly created by the user in regular tablespaces. Automatic undo stores the rollback segments in undo tablespace (SYS still uses the system tablespace).
In both mechanisms, blocks of rollback segments are written to redo.