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Don Burleson Blog 







PLS-00421 and ORA-04055 Encountered Tips

Expert Oracle Database Tips by Donald BurlesonMarch 9, 2015


Question:  :  My import gets the circular synonym error for some of my created types:

IMP-00003: ORACLE error 4055 encountered
ORA-04055: Aborted: "O_BULK_TARGET_SELECTOR" formed a non-REF mutually-dependent
    cycle with "T_GENERAL_IDLIST".
ORA-06550: line 5, column 25:
PLS-00421: circular synonym 'PUBLIC.T_GENERAL_IDLIST'  

How do I fix the ORA-04055 and PLS-00421 errors?

Answer: I have seen this error when the database contains invalid objects, start by ensuring that you had no invalid objects.  

Also, search MOSC for the ORA-04055 and PLS-00421 errors, there are known issues:

This can also generate the ORA-01775: looping chain of synonyms


 Let's start with the first error using oerr:  

ORA-04055: aborted: name formed a non-REF mutually-dependent cycle with name

Cause: This compilation was aborted because the library unit that was compiled would have formed a non-REF mutually-dependent cycle with some other library units. This happens when an attempt is made to compile types that have attributes of other types that may participate in a cycle with this type.

For example:
create type t1;
create type t2 (a t1);
create type t1 (a t2);

Action: Break the cycle (possibly by adding a REF or by using another type).

The oerr utility can display details on the PLS-00421 error:

PLS-00421: circular synonym 'string'  

Cause: Directly or indirectly, a synonym was defined in terms of itself, creating a circular definition.  

Action: Redefine the synonyms to eliminate the circular definition.

There are many ways to create synonyms, and you can often stop the recursive cycle by using REF operators.

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