Всем спасибо за помощь, для себя выбрал путь переопределения методов классов в приложении.
Добавляем метод в ORM (application/classes/ORM.php):
<?
class ORM extends Kohana_ORM {
public function use_index($index)
{
$this->_db_pending[] = array(
'name' => 'use_index',
'args' => array($index),
);
return $this;
}
}
И прописываем нужное в application/classes/Database/Query/Builder/Select.php
<?
class Database_Query_Builder_Select extends Kohana_Database_Query_Builder_Select {
protected $_use_index = NULL;
public function use_index($index)
{
$this->_use_index = $index;
return $this;
}
public function compile($db = NULL)
{
if ( ! is_object($db))
{
// Get the database instance
$db = Database::instance($db);
}
// Callback to quote columns
$quote_column = array($db, 'quote_column');
// Callback to quote tables
$quote_table = array($db, 'quote_table');
// Start a selection query
$query = 'SELECT ';
if ($this->_distinct === TRUE)
{
// Select only unique results
$query .= 'DISTINCT ';
}
if (empty($this->_select))
{
// Select all columns
$query .= '*';
}
else
{
// Select all columns
$query .= implode(', ', array_unique(array_map($quote_column, $this->_select)));
}
if ( ! empty($this->_from))
{
// Set tables to select from
$query .= ' FROM '.implode(', ', array_unique(array_map($quote_table, $this->_from)));
}
if ($this->_use_index !== NULL)
{
// Use index
$query .= " USE INDEX (" . $this->_use_index . ")";
}
if ( ! empty($this->_join))
{
// Add tables to join
$query .= ' '.$this->_compile_join($db, $this->_join);
}
if ( ! empty($this->_where))
{
// Add selection conditions
$query .= ' WHERE '.$this->_compile_conditions($db, $this->_where);
}
if ( ! empty($this->_group_by))
{
// Add grouping
$query .= ' '.$this->_compile_group_by($db, $this->_group_by);
}
if ( ! empty($this->_having))
{
// Add filtering conditions
$query .= ' HAVING '.$this->_compile_conditions($db, $this->_having);
}
if ( ! empty($this->_order_by))
{
// Add sorting
$query .= ' '.$this->_compile_order_by($db, $this->_order_by);
}
if ($this->_limit !== NULL)
{
// Add limiting
$query .= ' LIMIT '.$this->_limit;
}
if ($this->_offset !== NULL)
{
// Add offsets
$query .= ' OFFSET '.$this->_offset;
}
if ( ! empty($this->_union))
{
foreach ($this->_union as $u) {
$query .= ' UNION ';
if ($u['all'] === TRUE)
{
$query .= 'ALL ';
}
$query .= $u['select']->compile($db);
}
}
$this->_sql = $query;
return parent::compile($db);
}
}
На заметку, в методе compile я дописал строки в исходный метод compile
if ($this->_use_index !== NULL)
{
// USE INDEX
$query .= " USE INDEX (" . $this->_use_index . ")";
}
Теперь можно использовать ORM:
ORM::factory('Mp3')->use_index('artist_2')->where('artist', '=', $artist_name)->where('id', '>', $start_mp3_id)->order_by('id')->limit(10)->find_all();
