If you encounter the ORA-00845 error in Oracle, it means that the MEMORY_TARGET or MEMORY_MAX_TARGET parameter is not supported on the current system. This error can occur when trying to set the MEMORY_TARGET or MEMORY_MAX_TARGET parameter in the initialization parameter file (SPFILE) or when using the ALTER SYSTEM command to modify these parameters.
To diagnose and fix the ORA-00845 error, you can follow the steps below:
1. Check the Oracle documentation
– First, consult the Oracle documentation to understand the MEMORY_TARGET and MEMORY_MAX_TARGET parameters and their compatibility with your system. You can find detailed information in the Oracle Database Administrator’s Guide.
2. Verify system requirements
– Ensure that your system meets the requirements for using the MEMORY_TARGET and MEMORY_MAX_TARGET parameters. Check the minimum Oracle version, operating system, and hardware requirements for using these parameters.
3. Check parameter compatibility
– Use the V$OPTION view to check if the MEMORY_TARGET and MEMORY_MAX_TARGET parameters are supported on your system. You can run the following SQL query to check:
SELECT * FROM V$OPTION WHERE PARAMETER = 'Memory Target';
If the parameters are not supported, you will need to use alternative memory management methods.
4. Use Automatic Memory Management (AMM)
– If the MEMORY_TARGET and MEMORY_MAX_TARGET parameters are not supported, you can consider using Automatic Memory Management (AMM) instead. AMM dynamically manages the memory components in the SGA and PGA, and it does not require setting the MEMORY_TARGET or MEMORY_MAX_TARGET parameters.
To enable AMM, you can set the SGA_TARGET and PGA_AGGREGATE_TARGET parameters instead. Here’s an example of how to set these parameters:
ALTER SYSTEM SET SGA_TARGET=2G SCOPE=SPFILE; ALTER SYSTEM SET PGA_AGGREGATE_TARGET=500M SCOPE=SPFILE;
After setting these parameters, restart the database for the changes to take effect.
5. Consider manual memory management
– If AMM is not suitable for your system, you can consider using manual memory management by setting individual SGA and PGA parameters. This approach allows you to allocate specific sizes for the SGA and PGA components without using the MEMORY_TARGET or MEMORY_MAX_TARGET parameters.
You can set the SGA and PGA parameters using the ALTER SYSTEM command. Here’s an example of how to set the SGA_TARGET and PGA_AGGREGATE_TARGET parameters manually:
ALTER SYSTEM SET SGA_TARGET=2G SCOPE=SPFILE; ALTER SYSTEM SET PGA_AGGREGATE_TARGET=500M SCOPE=SPFILE;
After setting these parameters, restart the database for the changes to take effect.
By following these steps, you can diagnose and fix the ORA-00845 error in Oracle by ensuring that the MEMORY_TARGET and MEMORY_MAX_TARGET parameters are compatible with your system, and using alternative memory management methods if necessary. Remember to consult the Oracle documentation and seek assistance from Oracle support if you encounter any difficulties.
