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  1. MariaDB Server
  2. MDEV-6841

test decimal math

        Details

        • Type: Task
        • Status: Open
        • Priority: Major
        • Resolution: Unresolved
        • Fix Version/s: N/A
        • Component/s: None
        • Labels:
          None

          Description

          Even after all these years there is a steady stream of bugs in decimal math.
          We need a proactive approach instead, to try to find as many decimal bugs as
          possible.

          Suggestion: RQG testing of the expression

          ABS(CAST(a + b AS DOUBLE)/(CAST(a AS DOUBLE) + CAST(b AS DOUBLE)) - 1) < 0.0001

          where RQG randomly generates a and b, and the operation is one of +,
          -, *, /, mod.

          One should try also very small numbers (0.00...{~50 times}...01) as well as
          large ones.

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                relates to

                Bug - A problem which impairs or prevents the functions of the product. MDEV-6851 Decimal multiplication loses precision for no good reason

                • Minor - Minor loss of function, or other problem where easy workaround is present.
                • Open

                Bug - A problem which impairs or prevents the functions of the product. MDEV-6852 Sequence of decimal division and multiplications returns 0 instead of the real result

                • Minor - Minor loss of function, or other problem where easy workaround is present.
                • Open

                Bug - A problem which impairs or prevents the functions of the product. MDEV-6853 Unexpected zero result on 1 % <very small decimal> (wrong default precision of the returned result?)

                • Minor - Minor loss of function, or other problem where easy workaround is present.
                • Open

                Bug - A problem which impairs or prevents the functions of the product. MDEV-6856 <negative value> MOD <fractional divisor> returns negative zero

                • Minor - Minor loss of function, or other problem where easy workaround is present.
                • Open

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                  elenst Elena Stepanova added a comment -

                  This query works okay in 5.5.40 candidate, but wrong in MySQL 5.5 (apparently that's the same problem as the one Sergei Golubchik solved in the post-merge fix). 

                  MySQL [test]> select 0.0000000001 % 1;
+------------------+
| 0.0000000001 % 1 |
+------------------+
|     0.1000000000 |
+------------------+
1 row in set (0.00 sec)
                  Show
                  elenst Elena Stepanova added a comment - This query works okay in 5.5.40 candidate, but wrong in MySQL 5.5 (apparently that's the same problem as the one Sergei Golubchik solved in the post-merge fix). MySQL [test]> select 0.0000000001 % 1; +------------------+ | 0.0000000001 % 1 | +------------------+ | 0.1000000000 | +------------------+ 1 row in set (0.00 sec)

                    People

                    • Assignee:
                      elenst Elena Stepanova
                      Reporter:
                      serg Sergei Golubchik
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                      Dates

                      • Created:
                        Updated: