Adding Drupal nodes with a specific ID

As part of a drupal upgrade/migration I had a requirement to create a few thousand nodes with specific IDs. The internet said it could not be done but I did not believe it.

After diving into the bowels of the drupal code I found the spot which did the creating and it seemed to be doing something quite reasonable with the new node ID.

With just a small amount of convincing I managed to get it to do what I wanted.

diff -ru vanilla/drupal-7.12/modules/node/node.module web/drupal/modules/node/node.module
--- vanilla/drupal-7.12/modules/node/node.module        2012-02-02 09:03:14.000000000 +1100
+++ web/drupal/modules/node/node.module     2012-05-28 16:37:36.827171000 +1000
@@ -1095,6 +1095,12 @@
     if ($node->is_new) {
       // For new nodes, save new records for both the node itself and the node
       // revision.
+if(isset($node->request_nid))
+{
+       echo "Requested save new node with nid {$node->request_nid}\n";
+       $node->nid = $node->request_nid;
+       //print_r($node);
+}
       drupal_write_record('node', $node);
       _node_save_revision($node, $user->uid);
       $op = 'insert';

Creating a node can now be done like this:

$node = new stdClass();

$node->type = ...;

node_object_prepare($node);

// fill in node details here...
$node->request_nid = $my_nid;
node_save($node);

That seems quite trivial now. I don't know why so many people say it can't be done.