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| author | Alexey Kopytov <Alexey.Kopytov@sun.com> | 2009-03-27 13:12:50 +0300 |
|---|---|---|
| committer | Alexey Kopytov <Alexey.Kopytov@sun.com> | 2009-03-27 13:12:50 +0300 |
| commit | 0b60184b90cfb7ed1eb927e5106eb194677d43f7 (patch) | |
| tree | 25ffdefedc9a553afb5467a7752e34c85a3abbf9 /sql/field.cc | |
| parent | 510e9ddf36df94421f20e760225d69304f7a35f3 (diff) | |
| download | mariadb-git-0b60184b90cfb7ed1eb927e5106eb194677d43f7.tar.gz | |
Fix for bug #43432: Union on floats does unnecessary rounding
UNION could convert fixed-point FLOAT(M,D)/DOUBLE(M,D) columns
to FLOAT/DOUBLE when aggregating data types from the SELECT
substatements. While there is nothing particularly wrong with
this behavior, especially when M is greater than the hardware
precision limits, it could be confusing in cases when all
SELECT statements in a union have the same
FLOAT(M,D)/DOUBLE(M,D) columns with equal precision
specifications listed in the same position.
Since the manual is quite vague on what data type should be
returned in such cases, the bug was fixed by implementing the
most 'expected' behavior: do not convert FLOAT(M,D)/DOUBLE(M,D)
to anything else if all SELECT statements in a UNION have the
same precision for that column.
mysql-test/r/union.result:
Added a test case for bug #43432.
mysql-test/t/union.test:
Added a test case for bug #43432.
sql/field.cc:
Replaced FLT_DIG+6 and DBL_DIG+7 with a symbolic constant.
sql/item.cc:
Do not convert FLOAT(M,D)/DOUBLE(M,D)
to anything else if all SELECT statements in a UNION have the
same precision for that column.
sql/mysql_priv.h:
Added a symbolic constant for FLT_DIG+6 and DBL_DIG+7.
Diffstat (limited to 'sql/field.cc')
| -rw-r--r-- | sql/field.cc | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/sql/field.cc b/sql/field.cc index f8ab4b852ec..36cc4681dec 100644 --- a/sql/field.cc +++ b/sql/field.cc @@ -8587,16 +8587,16 @@ bool create_field::init(THD *thd, char *fld_name, enum_field_types fld_type, else if (tmp_length > PRECISION_FOR_FLOAT) { sql_type= FIELD_TYPE_DOUBLE; - length= DBL_DIG+7; /* -[digits].E+### */ + length= MAX_DOUBLE_STR_LENGTH; } else - length= FLT_DIG+6; /* -[digits].E+## */ + length= MAX_FLOAT_STR_LENGTH; decimals= NOT_FIXED_DEC; break; } if (!fld_length && !fld_decimals) { - length= FLT_DIG+6; + length= MAX_FLOAT_STR_LENGTH; decimals= NOT_FIXED_DEC; } if (length < decimals && |