2185{
2186 int index_am;
2187 Form_pg_class index_rel_form;
2188 HeapTuple index_rel_tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(index_oid));
2189
2190 if (!HeapTupleIsValid(index_rel_tuple))
2191 elog(ERROR, "cache lookup failed for index %u", index_oid);
2192
2193 index_rel_form = (Form_pg_class) GETSTRUCT(index_rel_tuple);
2194 index_am = index_rel_form->relam;
2195 ReleaseSysCache(index_rel_tuple);
2196 return index_am;
2197}