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From: Igor Korot <ikorot01@gmail.com>
Date: Thu, 18 Dec 2025 18:10:45 -0600
Message-ID: <CA+FnnTwZUo-ZRZ4if_ngXXkYgtOCsmMp1uFpsMFkG5AOmRxX4Q@mail.gmail.com>
Subject: Re: PQexecPrepared() question
To: "David G. Johnston" <david.g.johnston@gmail.com>
Cc: Laurenz Albe <laurenz.albe@cybertec.at>, 
	"pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>
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Hi, David,

On Thu, Dec 18, 2025 at 7:41=E2=80=AFAM David G. Johnston
<david.g.johnston@gmail.com> wrote:
>
> On Thu, Dec 18, 2025 at 8:20=E2=80=AFAM Igor Korot <ikorot01@gmail.com> w=
rote:
>>
>> Imagine following scenario:
>>
>> I have 2 machines. One is running PG server on *nix. Second is my app on=
 Windows.
>>
>> An application starts for the first time.
>>
>> What is =E2=80=9Cclientencoding in this case?
>
>
> This day in age, probably UTF-8; which is what most servers are initializ=
ed using.  If you aren't having issues with encoding I suggest you just tak=
e for granted that the defaults work in 99% of the cases.  If you are havin=
g issues, share the details.

My code:

         for( int i =3D 0; i < PQntuples( res ); i++ )
         {
             std::wstring cat =3D m_pimpl->m_myconv.from_bytes(
PQgetvalue( res, i, 0 ) );
             std::wstring schema =3D m_pimpl->m_myconv.from_bytes(
PQgetvalue( res, i, 1 ) );
             std::wstring table =3D m_pimpl->m_myconv.from_bytes(
PQgetvalue( res, i, 2 ) );
             char *table_owner =3D PQgetvalue( res, i, 3 );
             pimpl.m_tableDefinitions[cat].push_back( TableDefinition(
cat, schema,  table ) );
             count++;
             paramValues =3D schema + L"." + table;
             params[0] =3D new char[paramValues.length() + 2];
             memset( params[0], '\0', paramValues.length() + 2 );
             std::wcstombs( params[0], paramValues.c_str(),
paramValues.length() );
             params[1] =3D new char[table.length() + 2];
             memset( params[1], '\0', table.length() + 2 );
             std::wcstombs( params[1], table.c_str(), table.length() );
             params[2] =3D new char[schema.length() + 2];
             memset( params[2], '\0', schema.length() + 2 );
             std::wcstombs( params[2], schema.c_str(), schema.length() + 2 =
);
             paramFormat[0] =3D paramFormat[1] =3D paramFormat[2] =3D 0;
             paramLength[0] =3D paramValues.length();
             paramLength[1] =3D table.length();
             paramLength[2] =3D schema.length();
             res8 =3D PQexecPrepared( m_db, "set_table_prop", 3, params,
paramLength, paramFormat, 0 );
             if( PQresultStatus( res8 ) !=3D PGRES_COMMAND_OK )
             {
                 std::wstring err =3D m_pimpl->m_myconv.from_bytes(
PQerrorMessage( m_db ) );
                 errorMsg.push_back( L"Error executing query: " + err );
                 result =3D 1;
             }
             PQclear( res8 );
             delete[] params[0];
             params[0] =3D nullptr;
             delete[] params[1];
             params[1] =3D nullptr;
             delete[] params[2];
             params[2] =3D nullptr;
         }

And ths s what I have n the DB:

table_catalog | table_schema | table_name | table_type |
self_referencing_column_name | reference_generation |
user_defined_type_catalog | user_defined_type_schema |
user_defined_type_name | is_insertable_into | is_typed | commit_action
---------------+--------------+------------+------------+------------------=
------------+----------------------+---------------------------+-----------=
---------------+-
-----------------------+--------------------+----------+---------------
draft         | public       | abc=C3=9F       | BASE TABLE |
               |                      |                           |
                      |
                      | YES                | NO       |

Using my setup above and assumng my Win locale is en_US.UTF8 I can
successfullly retreve
that record but the insertion fails with

Invalid byte sequence for parameter $1 in UTF8

Thank you.

>
> David J.
>