Database: Static Contents in Disks
Instance: Processes/Threads and Memory running on a Database
A Database can only be opened by a single instance.
An instance can only open a single Database. And it dies when it cloese the Database.
SGA: A shared memory area by all the processes/threads of an instance
1.Conenction to a
Dedicated Server: Every connection occupies a exclusive server process. Too many connections may bring the server down.
2.Conenction to a
a. All the connections shared a single server process.(Pooling behind the scene)
b. Dispatcher + SGA Queues