A proprietary vendor supplied us with their code and details of performance for one of our teams to integrate with our existing systems. No news there, happens every day across the enterprise. However, as the implementation scaled it exposed fatal flaws in the proprietary code when under load - bringing everything to a grinding halt. As a consequence, we were obliged to rework the code for the vendor (having first pointed out all the flaws) – which entailed decompiling the Java, analysing and reworking it in order to get the system up and running again as well as additional improvements in the SQL queries. Because it was proprietary, there was no internal documentation available, no visibility of the code and no published schema to work with.