Normalize numeric values to Double for consistent filtering and serialization

Author: anidotnet

nitrite/src/main/java/org/dizitart/no2/common/DBValue.java

@@ -42,7 +42,7 @@ private DBValue() {
     }
 
     public DBValue(Comparable<?> value) {
-        this.value = value;
+        this.value = normalizeNumber(value);
     }
 
     @Override
@@ -58,6 +58,15 @@ public int compareTo(DBValue o) {
         return Comparables.compare(value, o.value);
     }
 
+    private static Comparable<?> normalizeNumber(Comparable<?> value) {
+        // Normalize all numeric types to Double for consistent serialization
+        // This ensures Integer(5) and Double(5.0) are treated the same in indexes
+        if (value instanceof Number && !(value instanceof Double)) {
+            return ((Number) value).doubleValue();
+        }
+        return value;
+    }
+
     private void writeObject(ObjectOutputStream stream) throws IOException {
         stream.writeObject(value);
     }