Thank you very much for taking the time to reply to my question.
I added oracle to search_path, but it didn't work.
postgres=# show search_path;
search_path
-------------------------------------
"$user", public, oracle, pg_catalog
At 2023-07-06 19:36:49, "Erik Wienhold" <ewie@ewie.name> wrote:
>> On 06/07/2023 11:19 CEST gzh <gzhcoder@126.com> wrote:
>>
>> I upgraded the version of PostgreSQL from 12.6 to 12.13,
>> when I execute the sql below , the to_char function caused the following error.
>>
>> ---------------SQL------------------
>> select TO_CHAR('1000000');
>>
>> ERROR: function to_char(unknown) is not unique at character 8
>> HINT: Could not choose a best candidate function. You might need to add explicit type casts.
>>
>> There is no problem before the upgrade and to_char function comes from the
>> Orafce extension.
>> The configuration of the old and new databases is as follows.
>>
>> Database server (old): PostgreSQL 12.6（orafce3.13）
>> Database server (new): PostgreSQL 12.13（orafce3.24）
>>
>> The new database has successfully installed the orafce 3.24 extension.
>> It does not occur in "PostgreSQL 12.6 and orafce 3.13",
>> but occurs in "PostgreSQL 12.13 and orafce 3.24",
>> so either the difference between 12.6 and 12.13 or the difference between
>> orafce 3.13 and 3.24 is suspicious.
>>
>> What is the reason for the problem and how to fix the error?
>
>This rings a bell:
>
>https://www.postgresql.org/message-id/1597875806.606392.1681915893771%40office.mailbox.org
>
>Either qualify functions with namespace oracle, e.g. oracle.to_char('1000000'),
>or place oracle on the search path.
>
>--
>Erik