Adding search_path has resolved this issue. But the problem is as follows where we won't be able to set search_path:
1> When trying to restore the data into a new DB server.
2> When we do an upgrade.
Right...which is why you cannot rely on setting a search_path but must instead arrange for everything, including the "=" operator, to be schema qualified.
But as per error message, it could be seen that the ltree type is found in util schema and the operator doesn't exist:
The ltree type wasn't "found" - its location is explicitly known to the system because the recorded data type for that column (in pg_attribute.atttype) includes an explicit schema location (in the related pg_type table). So the system sees "util.ltree" as opposed to "search_path=util; ltree".
The problem here is that "IS DISTINCT FROM" doesn't have any syntax for schema qualification and so the stored representation of your expression is impossible to record in a search_path agnostic way, unlike the create table example above. "NEW" is just a composite type of that table and thus has the same absolute references for the data types that comprise it. Hence my ewrite suggestion that allows you to write "operator(util.=)" in the stored expression thus providing a place for the schema qualification to exist (if you just write = there the system might do the operator rewrite for you in order to account for this dynamic.
With in the function, we have below entry for NEW."path" where we provide schema.type:
