How to Debug ORA-01775: Looping Chain of Synonyms?

Debugging ORA-01775: Looping Chain of Synonyms

The ORA-01775 error occurs when a synonym references another synonym, creating a circular dependency. While "create or replace" can resolve this issue, there are other techniques to aid in debugging.

Querying the Schema

To determine the current definition of a public synonym, execute the following query:

SELECT synonym_name, table_owner, table_name
FROM dba_synonyms
WHERE synonym_name = 'YOUR_SYNONYM_NAME';

This query will provide the owner and underlying table name associated with the synonym.

Identifying the Loop

To identify the looping chain, use the following steps:

1. Query dba_synonyms for the synonym in question.
2. Check the table_owner and table_name columns.
3. If the table_owner is not equal to the synonym's owner, query dba_synonyms again for the synonym with that owner and table name.
4. Repeat step 3 until the loop is identified or until you reach the base table.

Graphical Tools

While graphical tools specifically designed for debugging ORA-01775 are scarce, the following resources may be helpful:

• Oracle SQL Developer: Provides a graphical schema viewer that can help visualize object dependencies.
• Toad for Oracle: Offers a "Dependency Diagram" feature that displays objects and their relationships.

Other Considerations

• Looping chains can also occur when views reference synonyms or other views.
• Verify the existence of all objects referenced by synonyms before attempting to resolve the loop.
• In some cases, dropping and recreating the offending synonym may be necessary to break the loop.

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