Drupal 7 Module Development

Node Access
Instead, core returns the NODE_ACCESS_IGNORE constant, which indicates that
access to the View operation should be handled by the {node_access} table.
By default, the {node_access} table contains a single record:
nid gid realm grant_view grant_update grant_delete
0 0 all 1 0 0
This row allows the node access system to generate a default JOIN from the {node}
table to the {node_access} table that will always return TRUE.
However, if your site is not running any node access modules (that is, no modules
that implement hook_node_grants()), then no JOIN will be required. In this case,
all nodes will be returned.
If you install a node access module, however, you will immediately be prompted to
rebuild content access permissions for the site.
Rebuilding the permissions will update the {node_access} table with the rules
defined by the module(s) you have installed. When we activate the example module
we will be building in this chapter, here is the result:
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