>>>>> "Dan" == Dan Nelson <dnelson@stripped> writes:
Dan> In the last episode (Oct 27), sinisa@stripped said:
>> Dan Nelson writes:
>> > In the last episode (Oct 27), sinisa@stripped said:
>> > >
>> > > select floor(pow(2,63));
>> > >
>> > > returning negative result of -9223372036854775808.
>> > Mysql should either return some kind of error, or keep the result in
>> > double format internally, or use fixed-point math..
>> Yes, for X/OPen it is double, for ANSI SQL it is integer. Which one is
>> more relevant for MySQL ????
Dan> Dunno. Does ANSI SQL specify that the application must store the
Dan> number in a machine integral type? What's wrong with using a double
Dan> internally if the number doesn't fit in a longlong? For what it's
Dan> worth, the largest power that Oracle can process correctly is 2^132.
Dan> Past that it starts losing precision, but still works.
MySQL calculates floor() in double, but the default value for floor()
in integer/string context is integer. In the context:
select floor(xx), MySQL calculates the values of floor as a double,
but then cast the result to an integer.
If one uses floor() in a real number context like:
MySQL will return the answer as a double().
As MySQL doesn't have transactions and can't abort anywhere without
causing even more problems (as there isn't rollbacks), for example in
an update of type:
UPDATE table set A=floor(B);
it would not be good to stop halfways if B for one value would be
MySQL generally returns some 'reasonable' value for each expression
instead of generating an error (like 1/0 -> NULL). I know this is not
perfect, but the question is if this isn't good enough for most cases.
PS: In MySQL 3.23.6 I have at least fixed the problem with core
dumping on floor(pow(2,63)).