Hot & Cold Backup

A cold backup is a physical backup. During a cold backup the database is closed and not available to users.  All files of the database are copied (image copy).  The datafiles do not change during the copy so the database is in sync upon restore.
 

Used when:

Service level allows for some down time for backup

A hot backup is a physical backup.  In a hot backup the database remains open and available to users. All files of the database are copied (image copy).  There may be changes to the database as the copy is made and so all log files of changes being made during the backup must be saved too.  Upon a restore, the changes in the log files are reapplied to bring the database in sync.

Used when:

A full backup of a database is needed
Service level allows no down time for the backup

A logical backup is an extract of the database.  All SQL statements to create the objects and all SQL statements to populate the objects are included in the extract.  Oracle provides a utility export, to create the extract.   A partner utility, import, is used to bring the data back into the database.

A logical backup can be done at the table, schema (or proxy owner), or database level.  That is, we can extract only a list of specified tables, a list of specified schemas or the full database.

Used to:

Move or archive a database
Move or archive a table(s)
Move or archive a schema(s)
Verify the structures in the database