Upgrade node schema to the standard entity SQL schema: delete old fields.
function node_update_8018() {
$indexes = array(
'node_changed',
'node_created',
'node_frontpage',
'node_status_type',
'node_title_type',
'uid',
);
foreach ($indexes as $index) {
db_drop_index('node', $index);
}
$fields = array(
'title',
'uid',
'status',
'created',
'changed',
'comment',
'promote',
'sticky',
);
foreach ($fields as $field) {
db_drop_field('node', $field);
}
}