diff --git a/lib/ovsdb-data.c b/lib/ovsdb-data.c
index 0d7749b17..65fd43e69 100644
--- a/lib/ovsdb-data.c
+++ b/lib/ovsdb-data.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2009 Nicira Networks
+/* Copyright (c) 2009, 2010 Nicira Networks
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -65,6 +65,35 @@ ovsdb_atom_init_default(union ovsdb_atom *atom, enum ovsdb_atomic_type type)
     }
 }
 
+bool
+ovsdb_atom_is_default(const union ovsdb_atom *atom,
+                      enum ovsdb_atomic_type type)
+{
+    switch (type) {
+    case OVSDB_TYPE_VOID:
+        NOT_REACHED();
+
+    case OVSDB_TYPE_INTEGER:
+        return atom->integer == 0;
+
+    case OVSDB_TYPE_REAL:
+        return atom->real == 0.0;
+
+    case OVSDB_TYPE_BOOLEAN:
+        return atom->boolean == false;
+
+    case OVSDB_TYPE_STRING:
+        return atom->string[0] == '\0';
+
+    case OVSDB_TYPE_UUID:
+        return uuid_is_zero(&atom->uuid);
+
+    case OVSDB_N_TYPES:
+    default:
+        NOT_REACHED();
+    }
+}
+
 void
 ovsdb_atom_clone(union ovsdb_atom *new, const union ovsdb_atom *old,
                  enum ovsdb_atomic_type type)
@@ -351,6 +380,28 @@ ovsdb_datum_init_default(struct ovsdb_datum *datum,
     datum->values = alloc_default_atoms(type->value_type, datum->n);
 }
 
+bool
+ovsdb_datum_is_default(const struct ovsdb_datum *datum,
+                       const struct ovsdb_type *type)
+{
+    size_t i;
+
+    if (datum->n != type->n_min) {
+        return false;
+    }
+    for (i = 0; i < datum->n; i++) {
+        if (!ovsdb_atom_is_default(&datum->keys[i], type->key_type)) {
+            return false;
+        }
+        if (type->value_type != OVSDB_TYPE_VOID
+            && !ovsdb_atom_is_default(&datum->values[i], type->value_type)) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
 static union ovsdb_atom *
 clone_atoms(const union ovsdb_atom *old, enum ovsdb_atomic_type type, size_t n)
 {
diff --git a/lib/ovsdb-data.h b/lib/ovsdb-data.h
index 3f2d48943..18b8841c7 100644
--- a/lib/ovsdb-data.h
+++ b/lib/ovsdb-data.h
@@ -1,4 +1,4 @@
-/* Copyright (c) 2009 Nicira Networks
+/* Copyright (c) 2009, 2010 Nicira Networks
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -32,6 +32,7 @@ union ovsdb_atom {
 };
 
 void ovsdb_atom_init_default(union ovsdb_atom *, enum ovsdb_atomic_type);
+bool ovsdb_atom_is_default(const union ovsdb_atom *, enum ovsdb_atomic_type);
 void ovsdb_atom_clone(union ovsdb_atom *, const union ovsdb_atom *,
                       enum ovsdb_atomic_type);
 void ovsdb_atom_swap(union ovsdb_atom *, union ovsdb_atom *);
@@ -80,6 +81,8 @@ struct ovsdb_datum {
 };
 
 void ovsdb_datum_init_default(struct ovsdb_datum *, const struct ovsdb_type *);
+bool ovsdb_datum_is_default(const struct ovsdb_datum *,
+                            const struct ovsdb_type *);
 void ovsdb_datum_clone(struct ovsdb_datum *, const struct ovsdb_datum *,
                        const struct ovsdb_type *);
 void ovsdb_datum_destroy(struct ovsdb_datum *, const struct ovsdb_type *);
diff --git a/lib/uuid.c b/lib/uuid.c
index 264d9bf5a..620c039cb 100644
--- a/lib/uuid.c
+++ b/lib/uuid.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2008, 2009 Nicira Networks
+/* Copyright (c) 2008, 2009, 2010 Nicira Networks
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -107,6 +107,14 @@ uuid_zero(struct uuid *uuid)
     uuid->parts[0] = uuid->parts[1] = uuid->parts[2] = uuid->parts[3] = 0;
 }
 
+/* Returns true if 'uuid' is all zero, otherwise false. */
+bool
+uuid_is_zero(const struct uuid *uuid)
+{
+    return (!uuid->parts[0] && !uuid->parts[1]
+            && !uuid->parts[2] && !uuid->parts[3]);
+}
+
 /* Compares 'a' and 'b'.  Returns a negative value if 'a < b', zero if 'a ==
  * b', or positive if 'a > b'.  The ordering is lexicographical order of the
  * conventional way of writing out UUIDs as strings. */
diff --git a/lib/uuid.h b/lib/uuid.h
index 5dcaa25d8..1059c26d1 100644
--- a/lib/uuid.h
+++ b/lib/uuid.h
@@ -1,4 +1,4 @@
-/* Copyright (c) 2008, 2009 Nicira Networks
+/* Copyright (c) 2008, 2009, 2010 Nicira Networks
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -74,6 +74,7 @@ uuid_equals(const struct uuid *a, const struct uuid *b)
 void uuid_init(void);
 void uuid_generate(struct uuid *);
 void uuid_zero(struct uuid *);
+bool uuid_is_zero(const struct uuid *);
 int uuid_compare_3way(const struct uuid *, const struct uuid *);
 bool uuid_from_string(struct uuid *, const char *);
 
diff --git a/ovsdb/file.c b/ovsdb/file.c
index 97359d035..716ea89c5 100644
--- a/ovsdb/file.c
+++ b/ovsdb/file.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2009 Nicira Networks
+/* Copyright (c) 2009, 2010 Nicira Networks
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -261,8 +261,10 @@ ovsdb_file_replica_change_cb(const struct ovsdb_row *old,
             unsigned int idx = column->index;
 
             if (idx != OVSDB_COL_UUID && column->persistent
-                && (!old || !ovsdb_datum_equals(&old->fields[idx],
-                                                &new->fields[idx], type)))
+                && (old
+                    ? !ovsdb_datum_equals(&old->fields[idx], &new->fields[idx],
+                                          type)
+                    : !ovsdb_datum_is_default(&new->fields[idx], type)))
             {
                 if (!row) {
                     row = json_object_create();