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MDEV-17256 Decimal field multiplication bug.
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We should clear trailing zeroes in frac part. Otherwise
that tail is growing quickly and forces unnecessary truncating of
arguments.
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Alexey Botchkov committed Oct 30, 2018
1 parent 65cfc58 commit 5789831
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Showing 3 changed files with 105 additions and 16 deletions.
42 changes: 42 additions & 0 deletions mysql-test/r/type_newdecimal.result
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Original file line number Diff line number Diff line change
Expand Up @@ -1997,3 +1997,45 @@ select 0.0000000001 mod 1;
select 0.01 mod 1;
0.01 mod 1
0.01
CREATE TABLE t1 (
`FLD1` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD2` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD3` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD4` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD5` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD6` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD7` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD8` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD9` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD10` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD11` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD12` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD13` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD14` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD15` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD16` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD17` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD18` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD19` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD20` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD21` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD22` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD23` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000
);
INSERT INTO t1 VALUES (001.0760,000.9500,001.0000,001.0000,001.0000,
001.0000,001.0000,001.0000,001.0000,001.0000,001.0000,000.5949,001.0194,
001.0000,001.0000,001.0000,001.0000,001.0000,001.0000,000.9220,001.1890,001.2130,327.2690);
select FLD1*FLD2*FLD3*FLD4*FLD5*FLD6*FLD7*FLD8*FLD9*FLD10*FLD11*FLD12*FLD13*FLD14*FLD15*FLD16*FLD17*FLD18*FLD19*FLD20*FLD21*FLD22*FLD23 as calc1 from t1;
calc1
269.775757576440530322187032000000
select FLD23*FLD2*FLD1*FLD4*FLD5*FLD11*FLD12*FLD13*FLD3*FLD15*FLD16*FLD17*FLD18*FLD19*FLD20*FLD21*FLD22*FLD14*FLD6*FLD7*FLD8*FLD9*FLD10 as calc2 from t1;
calc2
269.775757576440530322187032000000
DROP TABLE t1;
CREATE TABLE t1 AS SELECT 1.0 * 2.000;
SHOW CREATE TABLE t1;
Table Create Table
t1 CREATE TABLE `t1` (
`1.0 * 2.000` decimal(6,4) NOT NULL DEFAULT '0.0000'
) ENGINE=MyISAM DEFAULT CHARSET=latin1
DROP TABLE t1;
44 changes: 44 additions & 0 deletions mysql-test/t/type_newdecimal.test
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Original file line number Diff line number Diff line change
Expand Up @@ -1581,3 +1581,47 @@ select 0.000000000000000000000000000000000000000000000000001 mod 1;
select 0.0000000001 mod 1;
select 0.01 mod 1;

#
# MDEV-17256 Decimal field multiplication bug
#

CREATE TABLE t1 (
`FLD1` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD2` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD3` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD4` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD5` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD6` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD7` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD8` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD9` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD10` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD11` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD12` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD13` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD14` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD15` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD16` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD17` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD18` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD19` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD20` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD21` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD22` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000,
`FLD23` decimal(7,4) unsigned zerofill NOT NULL DEFAULT 001.0000
);

INSERT INTO t1 VALUES (001.0760,000.9500,001.0000,001.0000,001.0000,
001.0000,001.0000,001.0000,001.0000,001.0000,001.0000,000.5949,001.0194,
001.0000,001.0000,001.0000,001.0000,001.0000,001.0000,000.9220,001.1890,001.2130,327.2690);

select FLD1*FLD2*FLD3*FLD4*FLD5*FLD6*FLD7*FLD8*FLD9*FLD10*FLD11*FLD12*FLD13*FLD14*FLD15*FLD16*FLD17*FLD18*FLD19*FLD20*FLD21*FLD22*FLD23 as calc1 from t1;
select FLD23*FLD2*FLD1*FLD4*FLD5*FLD11*FLD12*FLD13*FLD3*FLD15*FLD16*FLD17*FLD18*FLD19*FLD20*FLD21*FLD22*FLD14*FLD6*FLD7*FLD8*FLD9*FLD10 as calc2 from t1;

DROP TABLE t1;

CREATE TABLE t1 AS SELECT 1.0 * 2.000;
SHOW CREATE TABLE t1;
DROP TABLE t1;


35 changes: 19 additions & 16 deletions strings/decimal.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2077,26 +2077,21 @@ int decimal_mul(const decimal_t *from1, const decimal_t *from2, decimal_t *to)
}
}

/* Now we have to check for -0.000 case */
if (to->sign)
/* Remove trailing zero words in frac part */
frac0= ROUND_UP(to->frac);

if (frac0 > 0 && to->buf[intg0 + frac0 - 1] == 0)
{
dec1 *buf= to->buf;
dec1 *end= to->buf + intg0 + frac0;
DBUG_ASSERT(buf != end);
for (;;)
do
{
if (*buf)
break;
if (++buf == end)
{
/* We got decimal zero */
decimal_make_zero(to);
break;
}
}
frac0--;
} while (frac0 > 0 && to->buf[intg0 + frac0 - 1] == 0);
to->frac= DIG_PER_DEC1 * frac0;
}

/* Remove heading zero words in intg part */
buf1= to->buf;
d_to_move= intg0 + ROUND_UP(to->frac);
d_to_move= intg0 + frac0;
while (!*buf1 && (to->intg > DIG_PER_DEC1))
{
buf1++;
Expand All @@ -2109,6 +2104,14 @@ int decimal_mul(const decimal_t *from1, const decimal_t *from2, decimal_t *to)
for (; d_to_move--; cur_d++, buf1++)
*cur_d= *buf1;
}

/* Now we have to check for -0.000 case */
if (to->sign && to->frac == 0 && to->buf[0] == 0)
{
DBUG_ASSERT(to->intg <= DIG_PER_DEC1);
/* We got decimal zero */
decimal_make_zero(to);
}
return error;
}

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