[jboss-jira] [JBoss JIRA] (DROOLS-314) Build in accumulate functions are highly unreliable for long's and BigDecimals

[Davide Sottara (JIRA)]

     [ https://issues.jboss.org/browse/DROOLS-314?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Davide Sottara moved JBRULES-1322 to DROOLS-314:
------------------------------------------------

              Project: Drools  (was: JBRULES)
                  Key: DROOLS-314  (was: JBRULES-1322)
             Workflow: GIT Pull Request workflow   (was: classic default workflow)
    Affects Version/s:     (was: 4.0.3)
          Component/s:     (was: drools-compiler)
        Fix Version/s:     (was: FUTURE)

    
> Build in accumulate functions are highly unreliable for long's and BigDecimals
> ------------------------------------------------------------------------------
>
>                 Key: DROOLS-314
>                 URL: https://issues.jboss.org/browse/DROOLS-314
>             Project: Drools
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>            Reporter: Geoffrey De Smet
>            Assignee: Edson Tirelli
>            Priority: Critical
>         Attachments: JBRULES-1322-testcase.patch
>
>
> When dealing with financial data, one should never ever use double's. Instead BigDecimal should be used.
> Not because BigDecimal is bigger (that's rarely a problem) but because it doesn't do any decimal to binary transformation.
> For example, it's impossible for a double to correctly represent "0.2", aka 1/5.
> Summing many doubles (or even a few differing in scale), can easily give wrong results (and for financial data this tends to be important).
> Using doubles to sum longs have the exact same problem.
> Attached is a testcase patch which proves this by checking if (MAX_LONG - 4L) and 3L sum up to be (MAX_LONG - 1L).
> Currently they don't.
> One possible way to solve this is to fix JBRULES-1075,
> which just happens to give drools-solver 3% more performance ;) what a coincidence ^^

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