Finds bastard foreign keys in a database

BastardFinder.class.php

<?php 
if(!class_exists('Db'))
	require_once( dirname(__FILE__) . '/Db.class.php');

class BastardFinder 
{

	public $mysql, $mongo, $BastardBars, $BastardFoos;

	static private $instance;

	public function __construct()
	{
		$this->mysql = Db::PDOCreate('mysql://user:pass@localhost/dbname');
		$this->mongo = Db::MongoCreate();
	}

	public function getInstance() 
	{
		if(!isset(self::$instance))
		{
			self::$instance = new self;
		}
		return self::$instance;
	}

	public function findBastards() 
	{
		
		$sql = array(
			'BastardBars'=>array(
				'SELECT DISTINCT bar FROM table WHERE bar NOT IN (SELECT DISTINCT gid FROM legitrecords)'
				),
			'BastardFoos'=>array(
				'SELECT DISTINCT foo FROM bar WHERE foo NOT IN (
					SELECT DISTINCT foo FROM legitrecords UNION 
					SELECT DISTINCT foo2 FROM legitrecords UNION
					SELECT DISTINCT foo3 FROM legitrecords)',
				)
		); 

		$idsBuckets = array();

		foreach($sql as $k=>$queries)
		{
			foreach($queries as $query)
			{
				try
				{
					$stmt[$k] = $this->mysql->prepare($query);
					$stmt[$k]->execute(); 
					while( $row = $stmt[$k]->fetch(PDO::FETCH_NUM) ) 
					{
						if(is_integer($row[0])) 
						{
							$idsBuckets[$k][] = (int)$row[0];
						}
						else
						{
							$idsBuckets[$k][] = (string)$row[0];
						}

					}
				
				} 
				catch(PDOException $pdoe) 
				{
					echo $pdoe->getMessage();
				}
			}
		}


		foreach($idsBuckets as $bucketName=>$ids)
		{
			// Setup Indexes
			$this->mongo->createCollection($bucketName);
	        $this->mongo->$bucketName->deleteIndexes();
			$this->mongo->$bucketName->remove();
			$this->mongo->$bucketName->ensureIndex( array('_id'=>1),array('unique'=>1) );

		}


		foreach($idsBuckets as $bucketName=>$ids)
		{

			$ids = array_unique($ids);

			echo sprintf('Found %s %s %s', count($ids), $bucketName, PHP_EOL);
			foreach($ids as $id)
			{	
				$doc= (is_integer($id))  ? array('_id'=>(int)$id) : array('_id'=>(string)$id) ;
				$this->mongo->$bucketName->insert($doc, array('safe'=>true));
			}
		} 
		
	} 
}

BastardFinder::getInstance()->findBastards();