[jboss-jira] [JBoss JIRA] Commented: (JBRULES-1322) Build in accumulate functions are highly unreliable for long's and BigDecimals

Build in accumulate functions are highly unreliable for long's and BigDecimals ------------------------------------------------------------------------------ Key: JBRULES-1322 URL: http://jira.jboss.com/jira/browse/JBRULES-1322 Project: JBoss Drools Issue Type: Bug Security Level: Public(Everyone can see) Components: Drl Parser/Builder Affects Versions: 4.0.3 Reporter: Geoffrey De Smet Assigned To: Edson Tirelli Priority: Critical Fix For: 5.0.0-M1 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 ^^