Process and Runtime Limits

1)Instances per database
Maximum number of cluster database instances per database: Operating system-dependent

2)Locks
Row-level: Unlimited
Distributed Lock Manager: Operating system dependent

3)SGA size
Maximum value: Operating system-dependent;
For 32 bit OS, 2GB - 4GB.
For 64 bit OS, >4GB.

4)Advanced Queuing Processes
Maximum per instance: 10

5)Job Queue Processes
Maximum per instance: 1000

6)I/O Slave Processes
Maximum per background process (DBWR, LGWR, ....): 15
Maximum per Backup session: 15

7)Sessions
Maximum per instance: 32 KB; Restricted by the PROCESSES and SESSIONS initialization parameters.

8)Global Cache Service Processes
Maximum per instance: 10

9)Shared Servers
Maximum per instance: Unlimited. Restricted by the PROCESSES and SESSIONS initialization parameters.

10)Dispatchers
Maximum per instance: Unlimited. Restricted by the PROCESSES and SESSIONS initialization parameters.

11)Parallel Execution Slaves
Maximum per instance: Unlimited. Restricted by the PROCESSES and SESSIONS initialization parameters.

12)Backup Sessions
Maximum per instance: Unlimited. Restricted by the PROCESSES and SESSIONS initialization parameters.

Related Document
Physical Database Limits in oracle
Datatype Limits in Oracle
Logical Database Limits in Oracle