DMN Decision Table Hit Policies Explained – With Clear Examples
In DMN , Hit Policies define how the decision table evaluates rules and returns results . Misunderstanding hit policies is one of the most common causes of wrong decision outcomes in production . This blog explains: What DMN Hit Policies are All major hit policies ( FIRST, UNIQUE, ANY, COLLECT, PRIORITY ) Real-world examples Best practices (with Camunda DMN usage in mind) 1️⃣ What Is a DMN Hit Policy? A Hit Policy defines: How many rules can match Which result is returned if multiple rules match Without the correct hit policy: Decisions may return unexpected values Rules may conflict silently Production logic may break 2️⃣ FIRST – First Matching Rule Wins 🔹 Behavior Rules are evaluated top to bottom The first matching rule is returned Other matching rules are ignored 🧩 Example: Discount Calculation Customer Type Discount Premium 20% Regular 10% If customer = Premium → 20% ✅ Use when : Rules are ordered by priority Only one result should be returned ❌ Risk : Wrong rule or...