Datum
sequence_contained(PG_FUNCTION_ARGS)
{
    return DirectFunctionCall2(contains_sequence,
                               PG_GETARG_DATUM(1),
                               PG_GETARG_DATUM(0));
}

Datum
contains_sequence(PG_FUNCTION_ARGS)
{
    ArrayType              *a = PG_GETARG_ARRAYTYPE_P(0);
    ArrayType              *b = PG_GETARG_ARRAYTYPE_P(1);
    Oid                     element_type = ARR_ELEMTYPE(a);
    int                     na, nb;
    int                     i, j;
    char                   *pa;
    TypeCacheEntry         *typentry;
    FunctionCallInfoData    locfcinfo;
    Oid                     collation = PG_GET_COLLATION();

    if (array_contains_nulls(a) || array_contains_nulls(b))
        ereport(ERROR,
                (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                 errmsg("arrays must not contain nulls")));

    na = ArrayGetNItems(ARR_NDIM(a), ARR_DIMS(a));
    nb = ArrayGetNItems(ARR_NDIM(b), ARR_DIMS(b));
    pa = ARR_DATA_PTR(a);

    typentry = (TypeCacheEntry *) fcinfo->flinfo->fn_extra;
    if (typentry == NULL ||
        typentry->type_id != element_type)
    {
        typentry = lookup_type_cache(element_type,
                                     TYPECACHE_EQ_OPR_FINFO);
        if (!OidIsValid(typentry->eq_opr_finfo.fn_oid))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_FUNCTION),
            errmsg("could not identify an equality operator for type %s",
                   format_type_be(element_type))));

        fcinfo->flinfo->fn_extra = (void *) typentry;
    }

    InitFunctionCallInfoData(locfcinfo, &typentry->eq_opr_finfo, 2,
                             collation, NULL, NULL);

    for (i = 0; i <= na - nb; ++i)
    {
        char       *ppa = pa;
        char       *pb = ARR_DATA_PTR(b);

        for (j = 0; j < nb; ++j)
        {
            locfcinfo.arg[0] = fetch_att(ppa, typentry->typbyval, typentry->typlen);
            locfcinfo.arg[1] = fetch_att(pb, typentry->typbyval, typentry->typlen);
            locfcinfo.argnull[0] = false;
            locfcinfo.argnull[1] = false;
            locfcinfo.isnull = false;
            if (!DatumGetBool(FunctionCallInvoke(&locfcinfo)))
                break;

            pb = att_addlength_pointer(pb, typentry->typlen, pb);
            pb = (char *) att_align_nominal(pb, typentry->typalign);

            ppa = att_addlength_pointer(ppa, typentry->typlen, ppa);
            ppa = (char *) att_align_nominal(ppa, typentry->typalign);
        }

        if (j == nb)
            PG_RETURN_BOOL(true);

        pa = att_addlength_pointer(pa, typentry->typlen, pa);
        pa = (char *) att_align_nominal(pa, typentry->typalign);
    }

    PG_RETURN_BOOL(false);
}