2181{
2182 int index_am;
2183 Form_pg_class index_rel_form;
2184 HeapTuple index_rel_tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(index_oid));
2185
2186 if (!HeapTupleIsValid(index_rel_tuple))
2187 elog(ERROR, "cache lookup failed for index %u", index_oid);
2188
2189 index_rel_form = (Form_pg_class) GETSTRUCT(index_rel_tuple);
2190 index_am = index_rel_form->relam;
2191 ReleaseSysCache(index_rel_tuple);
2192 return index_am;
2193}