bool mongoc_cursor_set_hint (mongoc_cursor_t *cursor, uint32_t server_id);
Specifies which server to use for the operation. This function has an effect only if called before the find operation is executed.
(The function name includes the old term "hint" for the sake of backward compatibility, but we now call this number a "server id".)
Use mongoc_cursor_set_hint only for building a language driver that wraps the C Driver. When writing applications in C, leave the server id unset and allow the driver to choose a suitable server from the find operation's read preference.
true if successful, otherwise false and logs an error.