function _merge_cache()
{
if (count($this->ar_cache_exists) == 0) {
return;
}
foreach ($this->ar_cache_exists as $val) {
$ar_variable = 'ar_' . $val;
$ar_cache_var = 'ar_cache_' . $val;
if (count($this->{$ar_cache_var}) == 0) {
continue;
}
$this->{$ar_variable} = array_unique(array_merge($this->{$ar_cache_var}, $this->{$ar_variable}));
}
// If we are "protecting identifiers" we need to examine the "from"
// portion of the query to determine if there are any aliases
if ($this->_protect_identifiers === TRUE and count($this->ar_cache_from) > 0) {
$this->_track_aliases($this->ar_from);
}
}