| Bug #8464 | Precision math: AVG returns incorrect result | ||
|---|---|---|---|
| Submitted: | 12 Feb 2005 0:45 | Modified: | 7 Mar 2005 15:35 |
| Reporter: | Trudy Pelzer | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server | Severity: | S3 (Non-critical) |
| Version: | 5.0.3-alpha-debug | OS: | Linux (SuSE 9.1) |
| Assigned to: | Alexey Botchkov | CPU Architecture: | Any |
[7 Mar 2005 11:09]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/internals/22716
[7 Mar 2005 15:35]
Alexey Botchkov
Thank you for your bug report. This issue has been committed to our
source repository of that product and will be incorporated into the
next release.
If necessary, you can access the source repository and build the latest
available version, including the bugfix, yourself. More information
about accessing the source trees is available at
http://www.mysql.com/doc/en/Installing_source_tree.html
Description: The AVG of a set of decimals numbers is not being correctly calculated. How to repeat: mysql> create table t1 (col1 decimal(16,12)); Query OK, 0 rows affected (0.01 sec) mysql> insert into t1 values(-5.00000000001),(-5.00000000002),(-5.00000000003),(-5.00000000000),(-5.00000000001),(-5.00000000002); Query OK, 6 rows affected (0.00 sec) Records: 6 Duplicates: 0 Warnings: 0 mysql> insert into t1 select * from t1; Query OK, 6 rows affected (0.00 sec) Records: 6 Duplicates: 0 Warnings: 0 mysql> select col1,count(col1),sum(col1),avg(col1) from t1 group by col1\G *************************** 1. row *************************** col1: -5.000000000030 count(col1): 2 sum(col1): -10.000000000060 avg(col1): 3741823499999999499999999499999999499999999499999994.4999999994695000 *************************** 2. row *************************** col1: -5.000000000020 count(col1): 4 sum(col1): -20.000000000080 avg(col1): 2224127749999999749999999749999999749999999749999994.7499999997297500 *************************** 3. row *************************** col1: -5.000000000010 count(col1): 4 sum(col1): -20.000000000040 avg(col1): 2224127749999999749999999749999999749999999749999994.7499999997397500 *************************** 4. row *************************** col1: -5.000000000000 count(col1): 2 sum(col1): -10.000000000000 avg(col1): -5.0000000000000000 4 rows in set, 7 warnings (0.01 sec) -- In all cases, the AVG should be the same as the originally inserted value. All other functions shown provide the correct result.