MacLochlainns Weblog

The dbms_comparison package isn’t deployed when you provision a pluggable databases (PDBs) in Oracle 12c. It appears to be a simple omission. At least, it let me manually compiled the dbms_comparison package with this syntax:

@?/rdbms/admin/dbmscmp.sql
@?/rdbms/admin/prvtcmp.plb

However, when I ran the code against the PDB it failed. The same code worked against a container database (CDB). It struck me as odd. The error stack wasn’t too useful, as you can see below:

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BEGIN
*
ERROR at line 1:
ORA-06564: object "SYS"."COMPARE_NAME" does NOT exist
ORA-06512: at "SYS.DBMS_LOGREP_UTIL", line 569
ORA-06512: at "SYS.DBMS_LOGREP_UTIL", line 602
ORA-06512: at "SYS.DBMS_CMP_INT", line 394
ORA-01403: no DATA found
ORA-06512: at "SYS.DBMS_COMPARISON", line 764
ORA-06512: at line 2

My test was using two copies of a table with differences between column values. Both were deployed in the same CDB or PDB. That meant it was either a missing table or a problem with my database link. Here’s the statement that caused the failure:

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  dbms_comparison.create_comparison(comparison_name      => 'COMPARE_NAME'
                                   , schema_name         => 'video'
                                   , object_name         => 'MEMBER#1'
                                   , dblink_name         => 'loopbackpdb'
                                   , remote_schema_name  => 'video'
                                   , remote_object_name  => 'MEMBER#2');

Unfortunately, there wasn’t any notable difference between the two database links. Playing around with it, I discovered the problem. While you don’t have to enclose your case sensitive password in double quotes for a CDB database link, you do need to enclose the password with double quotes in a PDB database link.

This database link fixed the problem:

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CREATE DATABASE LINK loopbackpdb
  CONNECT TO video IDENTIFIED BY "Video1"
  USING 'video';

The delimiting double quotes on line 2 fixed the problem. Hopefully, this helps somebody who runs into it too. Any way, according to this June 2013 Oracle White Paper it would appear as a bug because it’s an inconsistent behavior between a CDB and PDB.