Steps to increase the size of SGA memory in Oracle

1. Check the SGA parameter which show the size of SGA allocated in Oracle

SQL> show parameter sga_

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
sga_max_size                         big integer 1536M
sga_min_size                         big integer 0
sga_target                           big integer 1536M
unified_audit_sga_queue_size         integer     1048576

2. Check the memory of your Operating system before increasing the SGA size.

3. Alter the size of SGA as required. I am increasing up to 2G;

SQL> ALTER SYSTEM SET SGA_MAX_SIZE=2G SCOPE=SPFILE;

System altered.

SQL> ALTER SYSTEM SET SGA_TARGET=2G SCOPE=SPFILE;

System altered.

Note: It is reommended to keep the SGA MAX SIZE value larger then SGA TARGET for future need, If we need in future than we can increase SGA TARGET without restart the database.

4. Restart the database for changes effect.

Shutdown immediate;
Startup;

5. Verify the changes are done.

SQL> show parameter sga_