[tarantool-patches] Re: [PATCH 6/6] sql: allow to specify UNSIGNED column type
n.pettik
korablev at tarantool.org
Wed Jul 17 03:54:41 MSK 2019
>>> --------------------------------------------------------------
>>> vdbeaux.c:2998:
>>> if ((f1 & MEM_UInt) != 0) {
>>> if ((f2 & MEM_Real) != 0) {
>>> return sqlIntFloatCompare(pMem1->u.i,
>>>
>>> pMem1 is unsigned, according to the first check,
>>> but you use u.i. Why?
>>
>> Thx, I’ve fixed series of similar places and extended sql/types.test.lua:
>>
>> diff --git a/src/box/sql/vdbeaux.c b/src/box/sql/vdbeaux.c
>> index 325c54c18..b6b5cd0bf 100644
>> --- a/src/box/sql/vdbeaux.c
>> +++ b/src/box/sql/vdbeaux.c
>> @@ -2887,43 +2887,50 @@ sqlBlobCompare(const Mem * pB1, const Mem * pB2)
>> return n1 - n2;
>> }
>>
>> -/*
>> - * Do a comparison between a 64-bit signed integer and a 64-bit floating-point
>> - * number. Return negative, zero, or positive if the first (i64) is less than,
>> - * equal to, or greater than the second (double).
>> +/**
>> + * Do a comparison between a 64-bit unsigned/signed integer and a
>> + * 64-bit floating-point number. Return negative, zero, or
>> + * positive if the first (integer) is less than, equal to, or
>> + * greater than the second (double).
>> */
>> static int
>> -sqlIntFloatCompare(i64 i, double r)
>> +compare_uint_float(uint64_t u, double r)
>
> Unfortunately, it is not as simple as you implemented it.
> See mp_compare_double_uint64 in tuple_compare.cc for details.
> In short, your function works wrong when numbers are near
> uint maximum. Perhaps, it is worth moving this comparator
> from tuple_compare.cc to a header. Like trivia/util.h.
Yep, I’m realising that :)
Unfortunately, sqlite uses such simplified version and there
are tests verifying this behaviour (boundary1/2/3 test suits).
Patch fixing it (as you suggest) is trivial, but it requires monotonous
test changes. Don’t you mind if I send it as follow-up after this
patch-set hits the trunk?
>> {
>> - if (sizeof(LONGDOUBLE_TYPE) > 8) {
>> - LONGDOUBLE_TYPE x = (LONGDOUBLE_TYPE) i;
>> - if (x < r)
>> - return -1;
>> - if (x > r)
>> - return +1;
>> - return 0;
>> - } else {
>> - i64 y;
>> - double s;
>> - if (r < -9223372036854775808.0)
>> - return +1;
>> - if (r > 9223372036854775807.0)
>> - return -1;
>> - y = (i64) r;
>> - if (i < y)
>> - return -1;
>> - if (i > y) {
>> - if (y == SMALLEST_INT64 && r > 0.0)
>> - return -1;
>> - return +1;
>> - }
>> - s = (double)i;
>> - if (s < r)
>> - return -1;
>> - if (s > r)
>> - return +1;
>> - return 0;
>> - }
>> + if (r > (double) UINT64_MAX)
>> + return -1;
>> + if (r < 0.0)
>> + return +1;
>> + uint64_t y = (uint64_t) r;
>> + if (u < y)
>> + return -1;
>> + if (u > y)
>> + return +1;
>> + double s = (double) u;
>> + if (s < r)
>> + return -1;
>> + if (s > r)
>> + return +1;
>> + return 0;
>> +}
>> +
>> +static int
>> +compare_int_float(int64_t i, double r)
>
> It has the same problems as the previous function,
> but can be fixed by calling compare_uint_float()
> with a modulo of 'int64_t i' and reversed result,
> if the value was negative. This is what mp_compare_double_any_int
> does.
>
>> +{
>> + if (r < (double) INT64_MIN)
>> + return +1;
>> + if (r >= 0.0)
>> + return -1;
>> + int64_t y = (int64_t) r;
>> + if (i < y)
>> + return -1;
>> + if (i > y)
>> + return +1;
>> + double s = (double) i;
>> + if (s < r)
>> + return -1;
>> + if (s > r)
>> + return +1;
>> + return 0;
>> }
>>> --------------------------------------------------------------
>>> vdbemem.c:1431:
>>> } else if (pVal->u.i == SMALLEST_INT64) {
>>> pVal->u.r = -(double)SMALLEST_INT64;
>>> MemSetTypeFlag(pVal, MEM_Real);
>>> } else {
>>> pVal->u.i = -pVal->u.i;
>>> }
>>>
>>> You compare u.i and SMALLEST_INT64, but you can't
>>> be sure, that u.i is not a big unsigned, can you?
>>
>> Fixed:
>>
>> diff --git a/src/box/sql/vdbemem.c b/src/box/sql/vdbemem.c
>> index f8673912e..64acb5d41 100644
>> --- a/src/box/sql/vdbemem.c
>> +++ b/src/box/sql/vdbemem.c
>> @@ -1428,11 +1428,15 @@ valueFromExpr(sql * db, /* The database connection */
>> return rc;
>> if (pVal->flags & MEM_Real) {
>> pVal->u.r = -pVal->u.r;
>> - } else if (pVal->u.i == SMALLEST_INT64) {
>> - pVal->u.r = -(double)SMALLEST_INT64;
>> - MemSetTypeFlag(pVal, MEM_Real);
>> - } else {
>> - pVal->u.i = -pVal->u.i;
>> + } else if ((pVal->flags & MEM_Int) != 0) {
>> + mem_set_u64(pVal, (uint64_t)(-pVal->u.i));
>> + } else if ((pVal->flags & MEM_UInt) != 0) {
>> + if (pVal->u.u > (uint64_t) INT64_MAX + 1) {
>> + pVal->u.r = -(double) pVal->u.u;
>> + MemSetTypeFlag(pVal, MEM_Real);
>
> Won't we have a problem here, that an expression '--value' won't be
> equal to 'value' in case the value is bigger than INT64_MAX + 1?
I guess it’s OK according to the original code. What is more, I doubt
that this path is reachable at all: both select -(-18446744073709551615)
and select -(18446744073709551615) queries result in error while
processing expr_code_int()..
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