Re: Postgres C-API: How to get the Oid for a custom type defined in a schema outside of the current search path

[Pavel Stehule]

Hi

čt 3. 12. 2020 v 10:32 odesílatel Michael Krüger <michael@kruegers.email>
napsal:

> Dear all,
>
> I need to find out the Oid of a custom type in C programming language.
> This type is defined in a schema, outside of the standard search path, e.g.
> public.
> I know that I can call TypenameGetTypid to find out an Oid. But this is
> not working for me if the type is not in the public namespace.
> How can I query a non-public Oid? Do I have to change the search path? If
> yes how do I do it? As mentioned I need to do this with the C interface.
>

I looking to source code

Oid
TypenameGetTypidExtended(const char *typname, bool temp_ok)
{
<-->Oid><--><-->typid;
<-->ListCell   *l;

<-->recomputeNamespacePath();

<-->foreach(l, activeSearchPath)
<-->{
<--><-->Oid><--><-->namespaceId = lfirst_oid(l);

<--><-->if (!temp_ok && namespaceId == myTempNamespace)
<--><--><-->continue;<-><--><-->/* do not look in temp namespace */

<--><-->typid = GetSysCacheOid2(TYPENAMENSP, Anum_pg_type_oid,
<--><--><--><--><--><--><--><-->PointerGetDatum(typname),
<--><--><--><--><--><--><--><-->ObjectIdGetDatum(namespaceId));
<--><-->if (OidIsValid(typid))
<--><--><-->return typid;
<-->}

<-->/* Not found in path */
<-->return InvalidOid;
}

You can get the value from sys cache by call GetSysCacheOid2. It can looks
like

<--><-->char<-->   *schemaname;
<--><-->char<-->   *typname;
<--><--><-->namespaceId = LookupExplicitNamespace(schemaname, missing_ok);
<--><--><-->if (OidIsValid(namespaceId))
<--><--><--><-->typoid = GetSysCacheOid2(TYPENAMENSP, Anum_pg_type_oid,
<--><--><--><--><--><--><--><--><--><--> PointerGetDatum(typname),
<--><--><--><--><--><--><--><--><--><--> ObjectIdGetDatum(namespaceId));
<--><--><-->else
<--><--><--><-->typoid = InvalidOid;


Regards

Pavel





> Regards,
> Michael
>
> Email: michael@kruegers.email
>