diff --git a/jOOQ/src/main/java/org/jooq/DataType.java b/jOOQ/src/main/java/org/jooq/DataType.java
index a437aaf1ee..5876d0b598 100644
--- a/jOOQ/src/main/java/org/jooq/DataType.java
+++ b/jOOQ/src/main/java/org/jooq/DataType.java
@@ -192,6 +192,8 @@ public interface DataType<T> extends Serializable {
 
     /**
      * Return a new data type like this, with a new nullability.
+     * <p>
+     * [#5709] A <code>nullable</code> column cannot have an {@link #identity()}.
      *
      * @param nullable The new nullability
      * @return The new data type
@@ -207,6 +209,9 @@ public interface DataType<T> extends Serializable {
 
     /**
      * Return a new data type like this, with a new identity flag.
+     * <p>
+     * [#5709] The IDENTITY flag imposes a NOT NULL constraint, and removes all
+     * DEFAULT values.
      *
      * @param identity The new identity flag
      * @return The new data type
@@ -223,6 +228,8 @@ public interface DataType<T> extends Serializable {
     /**
      * Specify an expression to be applied as the <code>DEFAULT</code> value for
      * this data type.
+     * <p>
+     * [#5709] A <code>defaulted</code> column cannot have an {@link #identity()}.
      *
      * @see #defaultValue(Field)
      */
diff --git a/jOOQ/src/main/java/org/jooq/impl/DefaultDataType.java b/jOOQ/src/main/java/org/jooq/impl/DefaultDataType.java
index 6b7b138833..4ba2957d83 100644
--- a/jOOQ/src/main/java/org/jooq/impl/DefaultDataType.java
+++ b/jOOQ/src/main/java/org/jooq/impl/DefaultDataType.java
@@ -363,7 +363,7 @@ public class DefaultDataType<T> implements DataType<T> {
 
     @Override
     public final DataType<T> nullable(boolean n) {
-        return new DefaultDataType<T>(this, precision, scale, length, n, identity, defaultValue);
+        return new DefaultDataType<T>(this, precision, scale, length, n, n ? false : identity, defaultValue);
     }
 
     @Override
@@ -373,7 +373,7 @@ public class DefaultDataType<T> implements DataType<T> {
 
     @Override
     public final DataType<T> identity(boolean i) {
-        return new DefaultDataType<T>(this, precision, scale, length, nullable, i, defaultValue);
+        return new DefaultDataType<T>(this, precision, scale, length, i ? false : nullable, i, i ? null : defaultValue);
     }
 
     @Override
@@ -388,7 +388,7 @@ public class DefaultDataType<T> implements DataType<T> {
 
     @Override
     public final DataType<T> defaultValue(Field<T> d) {
-        return new DefaultDataType<T>(this, precision, scale, length, nullable, identity, d);
+        return new DefaultDataType<T>(this, precision, scale, length, nullable, d != null ? false : identity, d);
     }
 
     @Override