MySQL Bugs: #5021: Format Function return different values on Windows and Linux

Bug #5021	Format Function return different values on Windows and Linux
Submitted:	12 Aug 2004 16:20	Modified:	29 Sep 2008 17:19
Reporter:	Felipe Riccetto	Email Updates:
Status:	Can't repeat	Impact on me:	None
Category:	MySQL Server	Severity:	S3 (Non-critical)
Version:	4.1.3b-beta-nt-max-log	OS:	Windows (Windows XP Pro)
Assigned to:	Konstantin Osipov	CPU Architecture:	Any

Description:
When I execute:

"select format(7.8960168039E11,6)"

on Windows XP Pro or Windows 2000 Server returns: "789,601,680,389.999880",
and on Linux (Fedora) returns = "789,601,680,390.00"

--------------------------
MySQL Version:
On Windows: 4.1.3b-beta-nt-max-log
On Linux: 4.1.3b-stantard

How to repeat:
Execute: "select format(7.8960168039E11,6)" on Windows and on Linux and see the returned values.

4.1.1 on windows returned the right result (same as linux),
4.1.3 somehow lost some precision here

Hi!

This is not a bug. Currently display of numbers is system dependent. We are looking into fixing 
this in a later release.

--Try to execute this test case:

create database test;
use test;

create table test (number double);

insert into test values(7.8960168039E11);

select number from test;
--the result is: 789601680390

--but when I execute the query below
select * from test where number=789601680390;
--it return 0 rows. This is, at least, strange...

--now, execute the query:
select format(number,6) from test
--it will return: 789,601,680,389.999880

Strange. But it is how Windows printf() rounds numbers when printing.
And for now MySQL relies of system printf() yet.

In the later releases we will do float->string conversion in MySQL, removing dependency on incompatible system implementations.

Hi!

This is a known and documented issue between versions. We will be looking at fixing this in a 
later release of MySQL.

Needs to be re-verified against the latest 6.0, which has dtoa.

This bug should be fixed by now. If it hasn't been yet, there is no design issue with fixing it any more.

I couldn't repeat anymore on Windows with 5.0/6.0 server.