by In a recent project, I encountered a frustrating issue while working with PostgreSQL. I had implemented a custom function that called another function (ST_X) as part of a table check constraint. Everything worked seamlessly—until I needed to back up the database and restore it on a new server.
When attempting to restore, I was ran into this error:
function st_x(geometry) does not exist.
HINT: No function matches the given name and argument types. You might need to add explicit type casts.After hours of troubleshooting, I discovered the root of the problem. PostgreSQL’s pg_restore utility sets the search_path to pg_catalog during the restoration process. This means that any custom functions relying on schema-qualified calls (like ST_X from postgis) fail to resolve, because they are not in the pg_catalog schema.
The Solution
The solution was to explicitly set the search_path for the affected functions. By defining a specific search path for these functions, they would no longer rely on the calling session’s search_path, avoiding potential conflicts or security risks.
Here’s the command that resolved the issue:
ALTER FUNCTION your_custom_function_name(geometry) SET search_path=public;This ensures that the function always uses the correct schema (public) for dependent operations, and it remains unaffected by pg_restore‘s default search_path setting of pg_catalog.
If you’re using custom functions, especially in constraints or triggers, consider setting their search_path explicitly. It’s a simple step that can save hours of troubleshooting.
