How to create a line-by-line comparison between the parameters used in two different databases

Here is a simple way to create a line-by-line comparison between two databases over a database link.

First make sure there is tns Connectivity between the database you execute the script in, and the remote database.

Then, create a datatabase link:

-- create db link from prod to test
create public database link testdb
connect to system
identified by ****
using 'testdb';

-- make sure that the link works before you proceed:
select host_name from v$instance@testdb;

The following script will spool a text file to your current directory, which can be investigated for differences between the two databases' initialization parameters:

set trimspool on
spool parameter_comparison.lst
set lines 200
col name format a40
col "test value" format a50
col "prod value" format a50
select prod.name,prod.value "prod value",test.value "test value"
from v$system_parameter prod full outer join v$system_parameter@testdb test
on prod.name = test.name;

exit