Narly

Narly is a simple module that allows an administrator to rebuild content permissions on a Drupal site without first wiping the node_access table.

Drupal sites occasionally need their node-access permissions rebuilt, but the rebuild functionality provided by the core node module deletes the contents of the node_access table before conducting the lengthy batch operation that repopulates the table, node by node. For sites with large numbers of nodes, rebuilding content permissions becomes a destructive operation, with user-facing pages appearing broken while the batch job repopulates the table.

This module adds a checkbox to the content-permissions-rebuild confirmation form at /admin/reports/status/rebuild. If checked, rebuild exhibits the core behavior and wipes the node_access table first. If left unchecked, the rebuild is performed without wiping the table first. Aside from making the initial table wipe optional, Narly changes nothing about the rebuild operation.

When the core rebuild operation loads each node, it deletes any existing node_access records for the node before creating new ones, so technically it's not necessary for it to wipe the table first. Narly takes advantage of this, but makes the table-wipe optional, in the event there's a legitimate need for it.

Why "Narly"? NAR = node access rebuild. And "ly" is just to make it cute.