diff --git a/agents/common/src/main/java/com/dbx/agent/DdlBuilder.java b/agents/common/src/main/java/com/dbx/agent/DdlBuilder.java
index 537904589f..222d233a10 100644
--- a/agents/common/src/main/java/com/dbx/agent/DdlBuilder.java
+++ b/agents/common/src/main/java/com/dbx/agent/DdlBuilder.java
@@ -218,8 +218,9 @@ public final class DdlBuilder {
     private static String columnTypeSql(ColumnInfo column) {
         String type = column.getData_type();
         String normalized = type.toLowerCase(Locale.ROOT);
-        if (isCharacterType(normalized) && column.getCharacter_maximum_length() != null) {
-            return type + "(" + column.getCharacter_maximum_length() + ")";
+        Integer characterLength = column.getCharacter_maximum_length();
+        if (isCharacterType(normalized) && characterLength != null && characterLength > 0) {
+            return type + "(" + characterLength + ")";
         }
         if (isNumericType(normalized) && column.getNumeric_precision() != null) {
             if (column.getNumeric_scale() != null) {
diff --git a/agents/drivers/kingbase/src/test/java/com/dbx/agent/kingbase/KingbaseAgentTest.java b/agents/drivers/kingbase/src/test/java/com/dbx/agent/kingbase/KingbaseAgentTest.java
index 58ade7266f..a9b6204c10 100644
--- a/agents/drivers/kingbase/src/test/java/com/dbx/agent/kingbase/KingbaseAgentTest.java
+++ b/agents/drivers/kingbase/src/test/java/com/dbx/agent/kingbase/KingbaseAgentTest.java
@@ -565,6 +565,23 @@ class KingbaseAgentTest extends JdbcFakeExecutionBehaviorTest {
         Assertions.assertFalse(ddl.contains("unknown metadata"), ddl);
     }
 
+    @Test
+    void ddlOmitsUnknownCharacterLengthSentinel() {
+        ColumnInfo unlimited = new ColumnInfo("display_name", "varchar", true, null, false, null, null, null, null, -1);
+
+        String ddl = DdlBuilder.buildTableDdl(
+            "public",
+            "accounts",
+            Collections.singletonList(unlimited),
+            Collections.emptyList(),
+            Collections.emptyList(),
+            true
+        );
+
+        Assertions.assertTrue(ddl.contains("`display_name` varchar"), ddl);
+        Assertions.assertFalse(ddl.contains("varchar(-1)"), ddl);
+    }
+
     @Test
     void regularListIndexesIncludesPrimaryUniqueAndSecondaryIndexes() {
         List<String> sql = new ArrayList<>();