[Tarantool-patches] [PATCH v1 3/4] sql: introduce cast for decimal

Safin Timur tsafin at tarantool.org
Mon Aug 16 22:34:16 MSK 2021


Oh, now I see the reasonable implicit and explicit casts table for 
decimals. I disavow my prior complain about missing directions for 
CAST(exprt AS DECIMAL).

Below there is minor complain though...

On 16.08.2021 18:57, Mergen Imeev via Tarantool-patches wrote:
> This patch introduces implicit and explicit cast of the DECIMAL field in
> SQL. Implicit cast to and from DECIMAL is precise. Explicit conversion
> to decimal and back could lead to loss of precision.
> 
> Part of #4415
> ---
>   src/box/sql/mem.c             | 334 ++++++++++++++++++++++++++++++-
>   test/sql-tap/decimal.test.lua | 366 +++++++++++++++++++++++++++++++++-
>   2 files changed, 695 insertions(+), 5 deletions(-)
> 
> diff --git a/src/box/sql/mem.c b/src/box/sql/mem.c
> index 016f0e80b..ff8b40d7f 100644
> --- a/src/box/sql/mem.c
> +++ b/src/box/sql/mem.c
> @@ -678,6 +678,17 @@ int_to_double_forced(struct Mem *mem)
>   	return CMP_OLD_NEW(i, d, int64_t);
>   }
>   
> +static inline int
> +int_to_dec(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_INT);
> +	int64_t i = mem->u.i;
> +	decimal_from_int64(&mem->u.d, i);
> +	mem->type = MEM_TYPE_DEC;
> +	mem->flags = 0;
> +	return 0;
> +}
> +
>   static inline int
>   uint_to_double_precise(struct Mem *mem)
>   {
> @@ -709,6 +720,17 @@ uint_to_double_forced(struct Mem *mem)
>   	return CMP_OLD_NEW(u, d, uint64_t);
>   }
>   
> +static inline int
> +uint_to_dec(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_UINT);
> +	int64_t u = mem->u.u;
> +	decimal_from_uint64(&mem->u.d, u);
> +	mem->type = MEM_TYPE_DEC;
> +	mem->flags = 0;
> +	return 0;
> +}
> +
>   static inline int
>   int_to_str0(struct Mem *mem)
>   {
> @@ -855,6 +877,19 @@ str_to_double(struct Mem *mem)
>   	return 0;
>   }
>   
> +static inline int
> +str_to_dec(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_STR);
> +	decimal_t dec;
> +	decimal_t *d;
> +	d = decimal_from_string(&dec, mem->z);
> +	if (d == NULL)
> +		return -1;
> +	mem_set_dec(mem, &dec);
> +	return 0;
> +}
> +
>   static inline int
>   double_to_int(struct Mem *mem)
>   {
> @@ -988,6 +1023,69 @@ double_to_uint_forced(struct Mem *mem)
>   	return res;
>   }
>   
> +static inline int
> +double_to_dec(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_DOUBLE);
> +	double d = mem->u.r;
> +	if (d >= 1e38 || d <= -1e38)
> +		return -1;
> +	decimal_from_double(&mem->u.d, d);
> +	mem->type = MEM_TYPE_DEC;
> +	mem->flags = 0;
> +	return 0;
> +}
> +
> +static inline int
> +double_to_dec_precise(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_DOUBLE);
> +	double d = mem->u.r;
> +	if (d >= 1e38 || d <= -1e38)
> +		return -1;
> +	decimal_t dec;
> +	decimal_from_double(&dec, d);
> +	if (atof(decimal_str(&mem->u.d)) != d)
> +		return -1;
> +	mem->u.d = dec;
> +	mem->type = MEM_TYPE_DEC;
> +	mem->flags = 0;
> +	return 0;
> +}
> +
> +/**
> + * Cast MEM with DOUBLE to DECIMAL. Doesn't fail. The return value is < 0
> if
> + * the original value is less than the result, > 0 if the original value
> is
> + * greater than the result, and 0 if the cast is precise.
> + */
> +static inline int
> +double_to_dec_forced(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_DOUBLE);
> +	double d = mem->u.r;
> +	mem->type = MEM_TYPE_DEC;
> +	mem->flags = 0;
> +	if (d >= 1e38) {
> +		const char *val =
> "99999999999999999999999999999999999999";
> +		assert(strlen(val) == 38);
> +		decimal_from_string(&mem->u.d, val);
> +		return 1;
> +	}
> +	if (d <= -1e38) {
> +		const char *val =
> "-99999999999999999999999999999999999999";
> +		assert(strlen(val) == 39);
> +		decimal_from_string(&mem->u.d, val);
> +		return -1;
> +	}
> +	decimal_from_double(&mem->u.d, d);
> +	double tmp = atof(decimal_str(&mem->u.d));
> +	if (d > tmp)
> +		return 1;
> +	if (d < tmp)
> +		return -1;
> +	return 0;
> +}
> +
>   static inline int
>   double_to_str0(struct Mem *mem)
>   {
> @@ -1001,6 +1099,173 @@ double_to_str0(struct Mem *mem)
>   	return 0;
>   }
>   
> +static inline int
> +dec_to_int(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_DEC);
> +	if (decimal_is_neg(&mem->u.d)) {
> +		int64_t i;
> +		if (decimal_to_int64(&mem->u.d, &i) == NULL)
> +			return -1;
> +		assert(i < 0);
> +		mem->u.i = i;
> +		mem->type = MEM_TYPE_INT;
> +		mem->flags = 0;
> +		return 0;
> +	}
> +	uint64_t u;
> +	if (decimal_to_uint64(&mem->u.d, &u) == NULL)
> +		return -1;
> +	mem->u.u = u;
> +	mem->type = MEM_TYPE_UINT;
> +	mem->flags = 0;
> +	return 0;
> +}
> +
> +static inline int
> +dec_to_int_precise(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_DEC);
> +	if (!decimal_is_int(&mem->u.d))
> +		return -1;
> +	return dec_to_int(mem);
> +}
> +
> +static inline int
> +dec_to_int_forced(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_DEC);
> +	if (decimal_is_neg(&mem->u.d)) {
> +		int64_t i;
> +		mem->type = MEM_TYPE_INT;
> +		mem->flags = 0;
> +		if (decimal_to_int64(&mem->u.d, &i) == NULL) {
> +			mem->u.i = INT64_MIN;
> +			return -1;
> +		}
> +		assert(i < 0);
> +		mem->u.i = i;
> +		/*
> +		 * Decimal is floored when cast to int, which means that
> after
> +		 * cast it becomes bigger if it was not integer.
> +		 */
> +		return decimal_is_int(&mem->u.d) ? 0 : -1;
> +	}
> +	uint64_t u;
> +	mem->type = MEM_TYPE_UINT;
> +	mem->flags = 0;
> +	if (decimal_to_uint64(&mem->u.d, &u) == NULL) {
> +		mem->u.u = UINT64_MAX;
> +		return 1;
> +	}
> +	mem->u.u = u;
> +	/*
> +	 * Decimal is floored when cast to uint, which means that after
> cast it
> +	 * becomes less if it was not integer.
> +	 */
> +	return decimal_is_int(&mem->u.d) ? 0 : 1;
> +}
> +
> +static inline int
> +dec_to_uint(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_DEC);
> +	uint64_t u;
> +	if (decimal_to_uint64(&mem->u.d, &u) == NULL)
> +		return -1;
> +	mem->u.u = u;
> +	mem->type = MEM_TYPE_UINT;
> +	mem->flags = 0;
> +	return 0;
> +}
> +
> +static inline int
> +dec_to_uint_precise(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_DEC);
> +	if (!decimal_is_int(&mem->u.d))
> +		return -1;
> +	return dec_to_uint(mem);
> +}
> +
> +static inline int
> +dec_to_uint_forced(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_DEC);
> +	uint64_t u;
> +	mem->type = MEM_TYPE_UINT;
> +	mem->flags = 0;
> +	if (decimal_to_uint64(&mem->u.d, &u) == NULL) {
> +		if (decimal_is_neg(&mem->u.d)) {
> +			mem->u.u = 0;
> +			return -1;
> +		}
> +		mem->u.u = UINT64_MAX;
> +		return 1;
> +	}
> +	mem->u.u = u;
> +	/*
> +	 * Decimal is floored when cast to uint, which means that after
> cast if
> +	 * if was not integer it becomes less if it was positive, and move
> if it
> +	 * was negative.
> +	 */
> +	if (decimal_is_int(&mem->u.d))
> +		return 0;
> +	return decimal_is_neg(&mem->u.d) ? -1 : 1;
> +}
> +
> +static inline int
> +dec_to_double(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_DEC);
> +	double r = atof(decimal_str(&mem->u.d));
> +	mem->u.r = r;
> +	mem->type = MEM_TYPE_DOUBLE;
> +	mem->flags = 0;
> +	return 0;
> +}
> +
> +static inline int
> +dec_to_double_precise(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_DEC);
> +	double r = atof(decimal_str(&mem->u.d));
> +	decimal_t d;
> +	decimal_t *dec = decimal_from_double(&d, r);
> +	if (dec == NULL || decimal_compare(dec, &mem->u.d) != 0)
> +		return -1;
> +	mem->u.r = r;
> +	mem->type = MEM_TYPE_DOUBLE;
> +	mem->flags = 0;
> +	return 0;
> +}
> +
> +static inline int
> +dec_to_double_forced(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_DEC);
> +	mem->type = MEM_TYPE_DOUBLE;
> +	mem->flags = 0;
> +	double r = atof(decimal_str(&mem->u.d));
> +	int res;
> +	decimal_t d;
> +	if (r <= -1e38)
> +		res = 1;
> +	else if (r >= 1e38)
> +		res = -1;
> +	else
> +		res = decimal_compare(&mem->u.d, decimal_from_double(&d,
> r));
> +	mem->u.r = r;
> +	return res;
> +}
> +
> +static inline int
> +dec_to_str0(struct Mem *mem)
> +{
> +	assert(mem->type == MEM_TYPE_DEC);
> +	return mem_copy_str0(mem, decimal_str(&mem->u.d));
> +}
> +
>   static inline int
>   bool_to_str0(struct Mem *mem)
>   {
> @@ -1053,6 +1318,8 @@ mem_to_int(struct Mem *mem)
>   		return str_to_int(mem);
>   	if (mem->type == MEM_TYPE_DOUBLE)
>   		return double_to_int(mem);
> +	if (mem->type == MEM_TYPE_DEC)
> +		return dec_to_int(mem);
>   	return -1;
>   }
>   
> @@ -1068,6 +1335,8 @@ mem_to_int_precise(struct Mem *mem)
>   		return str_to_int(mem);
>   	if (mem->type == MEM_TYPE_DOUBLE)
>   		return double_to_int_precise(mem);
> +	if (mem->type == MEM_TYPE_DEC)
> +		return dec_to_int(mem);
>   	return -1;
>   }
>   
> @@ -1083,6 +1352,8 @@ mem_to_double(struct Mem *mem)
>   		return int_to_double(mem);
>   	if (mem->type == MEM_TYPE_STR)
>   		return str_to_double(mem);
> +	if (mem->type == MEM_TYPE_DEC)
> +		return dec_to_double(mem);
>   	return -1;
>   }
>   
> @@ -1129,6 +1400,8 @@ mem_to_str0(struct Mem *mem)
>   		return array_to_str0(mem);
>   	case MEM_TYPE_UUID:
>   		return uuid_to_str0(mem);
> +	case MEM_TYPE_DEC:
> +		return dec_to_str0(mem);
>   	default:
>   		return -1;
>   	}
> @@ -1157,6 +1430,8 @@ mem_to_str(struct Mem *mem)
>   		return array_to_str0(mem);
>   	case MEM_TYPE_UUID:
>   		return uuid_to_str0(mem);
> +	case MEM_TYPE_DEC:
> +		return dec_to_str0(mem);
>   	default:
>   		return -1;
>   	}
> @@ -1177,6 +1452,8 @@ mem_cast_explicit(struct Mem *mem, enum field_type
> type)
>   			return str_to_uint(mem);
>   		case MEM_TYPE_DOUBLE:
>   			return double_to_uint(mem);
> +		case MEM_TYPE_DEC:
> +			return dec_to_uint(mem);
>   		default:
>   			return -1;
>   		}
> @@ -1209,9 +1486,21 @@ mem_cast_explicit(struct Mem *mem, enum field_type
> type)
>   	case FIELD_TYPE_NUMBER:
>   		return mem_to_number(mem);
>   	case FIELD_TYPE_DECIMAL:
> -		if (mem->type == MEM_TYPE_DEC)
> +		switch (mem->type) {
> +		case MEM_TYPE_INT:
> +			return int_to_dec(mem);
> +		case MEM_TYPE_UINT:
> +			return uint_to_dec(mem);
> +		case MEM_TYPE_STR:
> +			return str_to_dec(mem);
> +		case MEM_TYPE_DOUBLE:
> +			return double_to_dec(mem);
> +		case MEM_TYPE_DEC:
> +			mem->flags = 0;
>   			return 0;
> -		return -1;
> +		default:
> +			return -1;
> +		}

For consistency with majority of other numeric directions (mem_to_int(), 
mem_to_number(), mem_to_double()) I'd extract this code similarly to 
mem_to_decimal(). But this is up to you...


>   	case FIELD_TYPE_UUID:
>   		if (mem->type == MEM_TYPE_UUID) {
>   			mem->flags = 0;
...

> @@ -1296,9 +1591,19 @@ mem_cast_implicit(struct Mem *mem, enum field_type
> type)
>   		mem->flags = MEM_Number;
>   		return 0;
>   	case FIELD_TYPE_DECIMAL:
> -		if (mem->type == MEM_TYPE_DEC)
> +		switch (mem->type) {
> +		case MEM_TYPE_INT:
> +			return int_to_dec(mem);
> +		case MEM_TYPE_UINT:
> +			return uint_to_dec(mem);
> +		case MEM_TYPE_DOUBLE:
> +			return double_to_dec_precise(mem);
> +		case MEM_TYPE_DEC:
> +			mem->flags = 0;
>   			return 0;
> -		return -1;
> +		default:
> +			return -1;
> +		}
>   	case FIELD_TYPE_MAP:
>   		if (mem->type == MEM_TYPE_MAP)
>   			return 0;
> @@ -1343,6 +1648,8 @@ mem_cast_implicit_number(struct Mem *mem, enum
> field_type type)
>   			return -1;
>   		case MEM_TYPE_DOUBLE:
>   			return double_to_uint_forced(mem);
> +		case MEM_TYPE_DEC:
> +			return dec_to_uint_forced(mem);
>   		default:
>   			unreachable();
>   		}
> @@ -1353,6 +1660,8 @@ mem_cast_implicit_number(struct Mem *mem, enum
> field_type type)
>   			return int_to_double_forced(mem);
>   		case MEM_TYPE_UINT:
>   			return uint_to_double_forced(mem);
> +		case MEM_TYPE_DEC:
> +			return dec_to_double_forced(mem);
>   		case MEM_TYPE_DOUBLE:
>   			mem->flags = 0;
>   			return 0;
> @@ -1368,6 +1677,23 @@ mem_cast_implicit_number(struct Mem *mem, enum
> field_type type)
>   			return 0;
>   		case MEM_TYPE_DOUBLE:
>   			return double_to_int_forced(mem);
> +		case MEM_TYPE_DEC:
> +			return dec_to_int_forced(mem);
> +		default:
> +			unreachable();
> +		}
> +		break;
> +	case FIELD_TYPE_DECIMAL:
> +		switch (mem->type) {
> +		case MEM_TYPE_INT:
> +			return int_to_dec(mem);
> +		case MEM_TYPE_UINT:
> +			return uint_to_dec(mem);
> +		case MEM_TYPE_DEC:
> +			mem->flags = 0;
> +			return 0;
> +		case MEM_TYPE_DOUBLE:
> +			return double_to_dec_forced(mem);
>   		default:
>   			unreachable();
>   		}

Otherwise great patch, with the expected extension to explicit/implicit 
casts tables.

Thanks,
Timur


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