Re: BUG #17456: pg_dump creates dump that does not fully respect operator schema location

Ahh, that makes sense. Thank you for the thorough explanation. I wonder if
there's a good way to warn on this during the dump creation.

On Tue, Apr 5, 2022 at 12:05 PM David G. Johnston <
david(dot)g(dot)johnston(at)gmail(dot)com> wrote:

> On Tue, Apr 5, 2022 at 8:31 AM PG Bug reporting form <
> noreply(at)postgresql(dot)org> wrote:
>
>> The following bug has been logged on the website:
>>
>> Bug reference: 17456
>> Logged by: Andrew Grossman
>> Email address: agrossman(at)gmail(dot)com
>> PostgreSQL version: 14.2
>> Operating system: MacOS 12.3
>> Description:
>>
>> I have a case where an AFTER ROW trigger has a condition comparing two
>> ltree
>> fields. The ltree extension is installed in a different schema than the
>> triggered table is. Upon restoration, the following error is encountered:
>>
>> psql:/tmp/bugreport.sql:93: ERROR: 42883: operator does not exist:
>> util.ltree = util.ltree
>> LINE 1: ...N my_schema.my_table FOR EACH ROW WHEN ((new.path IS DISTINC...
>> ^
>> HINT: No operator matches the given name and argument types. You might
>> need
>> to add explicit type casts.
>> LOCATION: op_error, parse_oper.c:731
>>
>> The following sql will reproduce this case:
>>
>> SET SEARCH_PATH=my_schema,util;
>
> FOR EACH ROW WHEN ((new.path IS DISTINCT FROM old.path))
>>
>>
> Yes, this is a known limitation extending from our securing the
> search_path in order to fix a CVE.
>
> Casting to text works since it will use the system pg_catalog.=(text,text)
> operator.
>
> The other option is to avoid the indirection caused by IS DISTINCT FROM
> and write out the equivalent expression verbosely:
>
> not(new.path operator("util"."=") old.path) OR (new.path IS NULL AND
> old.path IS NULL)
>
> Another option is to add a SET search_path clause on the CREATE FUNCTION
> and move the WHEN check inside the function. When the trigger invokes the
> function the attached search_path will then be put into force and the
> resolution of =(lpath,lpath) will find the one in the util schema.
> Unfortunately, the create trigger command doesn't have a similar capability
> to attach a local setting value to it.
>
> David J.
>