Oracle Database basics 1

1. Oracle Database files are classified into five categories:
   1. Parameter files, data files, temporary files, control files, and redo log files.
2. Oralce Memory Structure
   1. System global zone (SGA)
   2. Process global zone (PGA)
   3. User global zone (UGA)
3. Differences between instances and databases
   1. Instance: A group of operating system processes and some memory
   2. Database: a group of related files (including data files and redo log files)
   3. Databases can be loaded by one or more instances (such as RAC)
   4. One instance can only load one database
4. View Oracle files in several dynamic views (you need to enter the database to query)
   1. V $ datafile (View data files)
   2. V $ logfile (view the redo log file group)
   3. V $ contrlfile (View control file)