Commit effe27e3 authored by mhansson/martin@linux-st28.site's avatar mhansson/martin@linux-st28.site
Browse files

Bug#33143: Incorrect ORDER BY for ROUND()/TRUNCATE() result 

The ROUND(X, D) function would change the Item::decimals field during
execution to achieve the effect of a dynamic number of decimal digits.
This caused a series of bugs:
Bug #30617:Round() function not working under some circumstances in InnoDB
Bug #33402:ROUND with decimal and non-constant cannot round to 0 decimal places
Bug #30889:filesort and order by with float/numeric crashes server
Fixed by never changing the number of shown digits for DECIMAL when
used with a nonconstant number of decimal digits.
parent 7f67efcc

mysql-test/r/type_decimal.result

+62 −1
Original line number Diff line number Diff line
@@ -797,7 +797,7 @@ dps tinyint(3) unsigned default NULL 
INSERT INTO t1 VALUES (1.1325,3);

SELECT ROUND(qty,3), dps, ROUND(qty,dps) FROM t1;

ROUND(qty,3)	dps	ROUND(qty,dps)

1.133	3	1.133

1.133	3	1.133000

DROP TABLE t1;

SELECT 1 % .123456789123456789123456789123456789123456789123456789123456789123456789123456789 AS '%';

%
@@ -805,3 +805,64 @@ SELECT 1 % .12345678912345678912345678912345678912345678912345678912345678912345 
SELECT MOD(1, .123456789123456789123456789123456789123456789123456789123456789123456789123456789) AS 'MOD()';

MOD()

0.012345687012345687012345687012345687012345687012345687012345687012345687000000000

CREATE TABLE t1( a DECIMAL(4, 3), b INT );

INSERT INTO t1 VALUES ( 1, 5 ), ( 2, 4 ), ( 3, 3 ), ( 4, 2 ), ( 5, 1 );

SELECT a, b, ROUND( a, b ) AS c FROM t1 ORDER BY c;

a	b	c

1.000	5	1.000

2.000	4	2.000

3.000	3	3.000

4.000	2	4.000

5.000	1	5.000

SELECT a, b, ROUND( a, b ) AS c FROM t1 ORDER BY c DESC;

a	b	c

5.000	1	5.000

4.000	2	4.000

3.000	3	3.000

2.000	4	2.000

1.000	5	1.000

CREATE TABLE t2 ( a INT, b INT, c DECIMAL(5, 4) );

INSERT INTO t2 VALUES ( 0, 1, 1.2345 ), ( 1, 2, 1.2345 ),

( 3, 3, 1.2345 ), ( 2, 4, 1.2345 );

SELECT a, b, MAX(ROUND(c, a)) 

FROM t2 

GROUP BY a, b 

ORDER BY b;

a	b	MAX(ROUND(c, a))

0	1	1.0000

1	2	1.2000

3	3	1.2350

2	4	1.2300

SELECT a, b, ROUND(c, a) 

FROM t2;

a	b	ROUND(c, a)

0	1	1.0000

1	2	1.2000

3	3	1.2350

2	4	1.2300

CREATE TABLE t3( a INT, b DECIMAL(6, 3) );

INSERT INTO t3 VALUES( 0, 1.5 );

SELECT ROUND( b, a ) FROM t3;

ROUND( b, a )

2.000

CREATE TABLE t4( a INT, b DECIMAL( 12, 0) );

INSERT INTO t4 VALUES( -9, 1.5e9 );

SELECT ROUND( b, a ) FROM t4;

ROUND( b, a )

2000000000

CREATE TABLE t5( a INT, b DECIMAL( 13, 12 ) );

INSERT INTO t5 VALUES( 0, 1.5 );

INSERT INTO t5 VALUES( 9, 1.5e-9 );

SELECT ROUND( b, a ) FROM t5;

ROUND( b, a )

2.000000000000

0.000000002000

CREATE TABLE t6( a INT );

INSERT INTO t6 VALUES( 6 / 8 );

SELECT * FROM t6;

a

1

SELECT ROUND(20061108085411.000002);

ROUND(20061108085411.000002)

20061108085411

DROP TABLE t1, t2, t3, t4, t5, t6;

mysql-test/t/type_decimal.test

+43 −0
Original line number Diff line number Diff line
@@ -416,3 +416,46 @@ DROP TABLE t1; 


SELECT 1 % .123456789123456789123456789123456789123456789123456789123456789123456789123456789 AS '%';

SELECT MOD(1, .123456789123456789123456789123456789123456789123456789123456789123456789123456789) AS 'MOD()';



#

# Bug #33143: Incorrect ORDER BY for ROUND()/TRUNCATE() result

#



CREATE TABLE t1( a DECIMAL(4, 3), b INT );

INSERT INTO t1 VALUES ( 1, 5 ), ( 2, 4 ), ( 3, 3 ), ( 4, 2 ), ( 5, 1 );

SELECT a, b, ROUND( a, b ) AS c FROM t1 ORDER BY c;

SELECT a, b, ROUND( a, b ) AS c FROM t1 ORDER BY c DESC;



CREATE TABLE t2 ( a INT, b INT, c DECIMAL(5, 4) );



INSERT INTO t2 VALUES ( 0, 1, 1.2345 ), ( 1, 2, 1.2345 ),

                      ( 3, 3, 1.2345 ), ( 2, 4, 1.2345 );



SELECT a, b, MAX(ROUND(c, a)) 

FROM t2 

GROUP BY a, b 

ORDER BY b;



SELECT a, b, ROUND(c, a) 

FROM t2;



CREATE TABLE t3( a INT, b DECIMAL(6, 3) );

INSERT INTO t3 VALUES( 0, 1.5 );

SELECT ROUND( b, a ) FROM t3;



CREATE TABLE t4( a INT, b DECIMAL( 12, 0) );

INSERT INTO t4 VALUES( -9, 1.5e9 );

SELECT ROUND( b, a ) FROM t4;



CREATE TABLE t5( a INT, b DECIMAL( 13, 12 ) );

INSERT INTO t5 VALUES( 0, 1.5 );

INSERT INTO t5 VALUES( 9, 1.5e-9 );

SELECT ROUND( b, a ) FROM t5;



CREATE TABLE t6( a INT );

INSERT INTO t6 VALUES( 6 / 8 );

SELECT * FROM t6;



SELECT ROUND(20061108085411.000002);



DROP TABLE t1, t2, t3, t4, t5, t6;

sql/item_func.cc

+6 −6
Original line number Diff line number Diff line
@@ -2008,7 +2008,7 @@ void Item_func_round::fix_length_and_dec() 
    int length_increase= ((decimals_delta <= 0) || truncate) ? 0:1;



    precision-= decimals_delta - length_increase;

    decimals= decimals_to_set;

    decimals= min(decimals_to_set, DECIMAL_MAX_SCALE);

    max_length= my_decimal_precision_to_length(precision, decimals,

                                               unsigned_flag);

    break;
@@ -2107,18 +2107,18 @@ my_decimal *Item_func_round::decimal_op(my_decimal *decimal_value) 
{

  my_decimal val, *value= args[0]->val_decimal(&val);

  longlong dec= args[1]->val_int();

  if (dec > 0 || (dec < 0 && args[1]->unsigned_flag))

  {

  if (dec >= 0 || args[1]->unsigned_flag)

    dec= min((ulonglong) dec, DECIMAL_MAX_SCALE);

    decimals= (uint8) dec; // to get correct output

  }

  else if (dec < INT_MIN)

    dec= INT_MIN;

    

  if (!(null_value= (args[0]->null_value || args[1]->null_value ||

                     my_decimal_round(E_DEC_FATAL_ERROR, value, (int) dec,

                                      truncate, decimal_value) > 1))) 

  {

    decimal_value->frac= decimals;

    return decimal_value;

  }

  return 0;

}

strings/decimal.c

+14 −2
Original line number Diff line number Diff line
@@ -1595,9 +1595,21 @@ decimal_round(decimal_t *from, decimal_t *to, int scale, 
      x+=10;

    *buf1=powers10[pos]*(x-y);

  }

  if (frac0 < 0)

  /*

    In case we're rounding e.g. 1.5e9 to 2.0e9, the decimal_digit_t's inside

    the buffer are as follows.



    Before <1, 5e8>

    After  <2, 5e8>



    Hence we need to set the 2nd field to 0.

    The same holds if we round 1.5e-9 to 2e-9.

   */

  if (frac0 < frac1)

  {

    dec1 *end=to->buf+intg0, *buf=buf1+1;

    dec1 *buf= to->buf + ((scale == 0 && intg0 == 0) ? 1 : intg0 + frac0);

    dec1 *end= to->buf + len;



    while (buf < end)

      *buf++=0;

  }