[MDEV-3661] LP:482846 - integer math errors with large numbers and no errors or warnings given Created: 2009-11-14  Updated: 2012-10-04  Resolved: 2012-10-04

Status: Closed
Project: MariaDB Server
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Bug
Reporter: archivist (Inactive) Assignee: Unassigned
Resolution: Won't Fix Votes: 0
Labels: Launchpad

Attachments: XML File LPexportBug482846.xml    

 Description   

mysql> select version();
-----------------------------

version()

-----------------------------

5.1.39-maria-beta-debug-log

-----------------------------
1 row in set (0.00 sec)

mysql> SELECT 4294967296 * 4294967296;
-------------------------

4294967296 * 4294967296

-------------------------

0

-------------------------
1 row in set (0.00 sec)

mysql> show warnings;
Empty set (0.00 sec)

mysql> SELECT 3037000500 * 3037000500;
-------------------------

3037000500 * 3037000500

-------------------------

-9223372036709301616

-------------------------
1 row in set (0.00 sec)

mysql> show warnings;
Empty set (0.00 sec)

mysql> SELECT 4294967296 * 4294967297;
-------------------------

4294967296 * 4294967297

-------------------------

4294967296

-------------------------
1 row in set (0.00 sec)

mysql> show warnings;
Empty set (0.00 sec)

mysql> SELECT 4294967296 * 4294967298;
-------------------------

4294967296 * 4294967298

-------------------------

8589934592

-------------------------
1 row in set (0.00 sec)

mysql> show warnings;
Empty set (0.00 sec)

mysql> SELECT 4294967296.0 * 4294967298.0;
-----------------------------

4294967296.0 * 4294967298.0

-----------------------------

18446744082299486208.00

-----------------------------
1 row in set (0.08 sec)

mysql> show warnings;
Empty set (0.00 sec)

mysql> quit;
Bye
archivist@cnc:~/archivist-cnc/archivist-cnc/build/mysql-test$ uname -a
Linux cnc 2.6.24-16-rtai #1 Tue Sep 30 22:54:33 EEST 2008 i686 GNU/Linux

adding a .0 to the large number gets it to use float/double maths, the integer maths does not seem to check its range or overflow conditions correctly thus giving incorrect results.

  1. Bug#xxxxx: Reproducible MariaDB server integer math fault
    #
  2. this returns 0 incorrectly it appears to be the left side * 0
    --exec $MYSQL test -e "SELECT 4294967296 * 4294967296\g" 2>&1
    #
  3. this gives an incorrect negative number
    --exec $MYSQL test -e "SELECT 3037000500 * 3037000500\g" 2>&1
    #
  4. this returns 4294967296 the number on the left times 1
    --exec $MYSQL test -e "SELECT 4294967296 * 4294967297\g" 2>&1
    #
  5. this returns 8589934592 the number on the left times 2
    --exec $MYSQL test -e "SELECT 4294967296 * 4294967298\g" 2>&1
    #
  6. this seems to be correct it has cast to a float/double
    --exec $MYSQL test -e "SELECT 4294967296.0 * 4294967298.0;\g" 2>&1

 Comments   
Comment by Michael Widenius [ 2009-11-17 ]

Re: integer math errors with large numbers and no errors or warnings given
The issue is that you are using integer arithmetic, which is described at:
http://dev.mysql.com/doc/refman/5.1/en/arithmetic-functions.html

Not much we can do with this, as we are trying to be compatible with MySQL.

We should however consider to find a way to create a warning in cases when you get overflow.

I will create a worklog entry for this.

Comment by Rasmus Johansson (Inactive) [ 2009-11-17 ]

Launchpad bug id: 482846

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