public function getExpansions($storeId)
{
$connection = $this->getConnection();
$select = $this->getBaseSelect($storeId, ThesaurusInterface::TYPE_EXPANSION);
$select->join(['expanded_terms' => $this->getTable(ThesaurusInterface::REFERENCE_TABLE_NAME)], 'expanded_terms.term_id = terms.term_id AND expanded_terms.thesaurus_id = terms.thesaurus_id', []);
$select->columns(['terms' => new \Zend_Db_Expr('CONCAT(expanded_terms.term, " => " ,GROUP_CONCAT(terms.term))')]);
return $connection->fetchCol($select);
}