What is undo and redo logs in Oracle?
The main difference between undo and redo in Oracle is that undo helps in rollback and maintaining read consistency while redo helps in rolling forward database changes. Undo is a record of a transaction before it is committed. On the other hand, redo is an entry in redo log files that holds a group of change vectors.
Can you take partial backup if the database is running in Noarchivelog mode?
In summary, if a database is operated in NOARCHIVELOG mode, a full backup is the only method to partially protect the database against a disk failure; if a database is operating in ARCHIVELOG mode, the files assembled by a full backup can be used to restore damaged files as part of database recovery from a disk failure …
What is redo in database?
A redo record, also called a redo entry, is made up of a group of change vectors, each of which is a description of a change made to a single block in the database. Redo entries record data that you can use to reconstruct all changes made to the database, including the undo segments.
How do you go forward instead of undo?
To undo an action, press Ctrl + Z. To redo an undone action, press Ctrl + Y.
Do you have to open Oracle keystore for media recovery?
If you perform media recovery on an encrypted database or tablespace, then the Oracle keystore must be open when performing media recovery. See Oracle Database Administrator’s Guide to learn about encrypted tablespaces.
Can a snapshot of Oracle database be used for recovery?
Take care that the database snapshots are usable. Oracle Database does not use a snapshot for recovery if structural changes were made during the snapshot. Some SQL operations can make database structural changes and should not be used during a snapshot.
How to recover the root of the database?
To recover the whole CDB, the root, or multiple PDBs, you connect to the root. To recover a particular PDB, connect to that PDB. To recover PDBs, you use the RECOVER PLUGGABLE DATABASE command. To recover a whole CDB, use the RECOVER DATABASE command and to recover the root, use the RECOVER DATABASE ROOT command.