Steps 1:- Create database link in first instance


create database link indian
connect to apps identified by apps
using
'(DESCRIPTION=
(ADDRESS=
(PROTOCOL=TCP)
(HOST=prod.indiandba.com)
(PORT=10510))
(CONNECT_DATA=
(SID=PROD)))'
/

Steps 2:- use bellow query to find difference bitween tables

select patch_name 

  from 

(

( select patch_name from ad_applied_patches

  minus 

  select patch_name from ad_applied_patches@indian )

union all

( select patch_name from ad_applied_patches@indian

  minus

  select patch_name from ad_applied_patches )

)

select BUG_NUMBER 

  from 

(

( select BUG_NUMBER from ad_bugs

  minus 

  select BUG_NUMBER from ad_bugs@indian )

union all

( select BUG_NUMBER from ad_bugs@indian

  minus

  select BUG_NUMBER from ad_bugs )

)

-----OR-------

SELECT patch_name FROM ad_applied_patches

MINUS

SELECT patch_name FROM ad_applied_patches@indian

SELECT BUG_NUMBER FROM ad_bugs

MINUS

SELECT BUG_NUMBER FROM ad_bugs@indian