Respond to updates to a node.
This hook is invoked only on the module that defines the node's content type (use hook_node_update() to act on all node updates).
This hook is invoked from $node->save() after the node is updated in the node table in the database, before field_attach_update() is called, and before hook_node_update() is invoked.
\Drupal\Core\Entity\EntityInterface $node: The node that is being updated.
Note: this list is generated by pattern matching, so it may include some functions that are not actually implementations of this hook.
function hook_update(\Drupal\Core\Entity\EntityInterface $node) {
db_update('mytable')
->fields(array(
'extra' => $node->extra,
))
->condition('nid', $node->nid)
->execute();
}