ORA-00821: Specified value of sga_target 5120M is too small, needs to be at least 12352M

There could be situations where you are trying to start your database instance, however, it returns an error message instead of starting up. Such errors are mostly related to init parameters and must be fixed before retrying to start the instance. Issue could be related to an invalid value of a parameter or syntax error in the parameter file. In the following I will explain one of the errors that are related to an invalid value of parameter SGA_TARGET.

ORA-04036: PGA memory used by the instance exceeds PGA_AGGREGATE_LIMIT

This is a very critical error message that many applications started seeing since 12c. Prior to 12c, PGA of a server process could grow unabatedly. After the advent of PGA_AGGREGATE_LIMIT, PGA usage for all connected sessions could be limited to avoid enormous growth of PGA memory due to bad PL/SQL code (or due to an Oracle bug causing a process memory leak). Whenever total PGA usage by all sessions tries to go beyond the value set in this parameter, ORA-04036 is returned to the session and also logged in the alert log file (and trace file is also generated) . Alert log file could log error message similar to the following.

ORA-13792: This operation requires a database link

There could be other reasons for this message to appear while you are trying to execute something in a standby database (or perhaps on primary database), however, in my case, this message was returned when I was trying to create an SQL Tuning Advisor task and wanted to submit for advisor’s recommendations. While doing so, I did not realize that I was actually trying to execute this on physical standby database. Following is the entire error stack that was returned.