Function refnameNamespaceItem

src/backend/parser/parse_relation.c:114–166

* refnameNamespaceItem * Given a possibly-qualified refname, look to see if it matches any visible * namespace item. If so, return a pointer to the nsitem; else return NULL. * * Optionally get nsitem's nesting depth (0 = current) into *sublevels_up. * If sublevels_up is NULL, only consider items at the current nesting * level. * * An unqualified refname (schemaname == NULL) can

 * peculiar, but it's what SQL says to do.
 */
ParseNamespaceItem *
refnameNamespaceItem(ParseState *pstate,
					 const char *schemaname,
					 const char *refname,
					 int location,
					 int *sublevels_up)
{
	Oid			relId = InvalidOid;

	if (sublevels_up)
		*sublevels_up = 0;

	if (schemaname != NULL)
	{
		Oid			namespaceId;

		/*
		 * We can use LookupNamespaceNoError() here because we are only
		 * interested in finding existing RTEs.  Checking USAGE permission on
		 * the schema is unnecessary since it would have already been checked
		 * when the RTE was made.  Furthermore, we want to report "RTE not
		 * found", not "no permissions for schema", if the name happens to
		 * match a schema name the user hasn't got access to.
		 */
		namespaceId = LookupNamespaceNoError(schemaname);
		if (!OidIsValid(namespaceId))
			return NULL;
		relId = get_relname_relid(refname, namespaceId);
		if (!OidIsValid(relId))
			return NULL;
	}

	while (pstate != NULL)
	{
		ParseNamespaceItem *result;

		if (OidIsValid(relId))
			result = scanNameSpaceForRelid(pstate, relId, location);
		else
			result = scanNameSpaceForRefname(pstate, refname, location);

		if (result)
			return result;

		if (sublevels_up)
			(*sublevels_up)++;
		else
			break;

		pstate = pstate->parentParseState;
	}
	return NULL;
}

/*
 * Search the query's table namespace for an item matching the