[tarantool-patches] Re: [PATCH 6/6] sql: allow to specify UNSIGNED column type

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

Thanks for the fixes!

>> --------------------------------------------------------------
>> 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.

>  {
> -       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?

> +                               } else {
> +                                       mem_set_i64(pVal, (int64_t)(-pVal->u.u));
> +                               }
>                         }
>                         sql_value_apply_type(pVal, type);
>                 }
> 

Note for Kirill: this is not a final review. I will get back a bit later to
check other places where Mem.u.u, Mem.u.i, MEM_UInt, MEM_Int are used.