diff --git a/lib/dns/db.c b/lib/dns/db.c
index 9751d1e017..cf92447eec 100644
--- a/lib/dns/db.c
+++ b/lib/dns/db.c
@@ -201,6 +201,24 @@ dns_db_newversion(dns_db_t *db, dns_dbversion_t **versionp) {
 	return ((db->methods->newversion)(db, versionp));
 }
 
+void
+dns_db_attachversion(dns_db_t *db, dns_dbversion_t *source,
+		     dns_dbversion_t **targetp)
+{
+	/*
+	 * Attach '*targetp' to 'source'.
+	 */
+
+	REQUIRE(DNS_DB_VALID(db));
+	REQUIRE((db->attributes & DNS_DBATTR_CACHE) == 0);
+	REQUIRE(source != NULL);
+	REQUIRE(targetp != NULL && *targetp != NULL);
+
+	(db->methods->attachversion)(db, source, targetp);
+
+	ENSURE(*targetp != NULL);
+}	
+
 void
 dns_db_closeversion(dns_db_t *db, dns_dbversion_t **versionp,
 		    isc_boolean_t commit)
diff --git a/lib/dns/include/dns/db.h b/lib/dns/include/dns/db.h
index 3df54d2b5a..a088a66c99 100644
--- a/lib/dns/include/dns/db.h
+++ b/lib/dns/include/dns/db.h
@@ -78,6 +78,8 @@ typedef struct dns_dbmethods {
 					  dns_dbversion_t **versionp);
 	dns_result_t	(*newversion)(dns_db_t *db,
 				      dns_dbversion_t **versionp);
+	void		(*attachversion)(dns_db_t *db, dns_dbversion_t *source,
+					 dns_dbversion_t **targetp);
 	void		(*closeversion)(dns_db_t *db,
 					dns_dbversion_t **versionp,
 					isc_boolean_t commit);
@@ -346,6 +348,25 @@ dns_db_newversion(dns_db_t *db, dns_dbversion_t **versionp);
  *	implementation used.
  */
 
+void
+dns_db_attachversion(dns_db_t *db, dns_dbversion_t *source,
+		     dns_dbversion_t **targetp);
+/*
+ * Attach '*targetp' to 'source'.
+ *
+ * Requires:
+ *
+ *	'db' is a valid database with zone semantics.
+ *
+ *	source is a valid open version
+ *
+ *	targetp != NULL && *targetp == NULL
+ *
+ * Ensures:
+ *
+ *	'*targetp' is attached to source.
+ */
+
 void
 dns_db_closeversion(dns_db_t *db, dns_dbversion_t **versionp,
 		    isc_boolean_t commit);