I was given an hour to mass-rename 100k files in various folders. challenge accepted. (and the script took 5 minutes)

sorter.py

import os
import MySQLdb
import re

class ImageSorter(object):
  	
	def __init__(self, base_directory):
		self.cur = MySQLdb.connect(host='127.0.0.1', user="root", db="magento").cursor() # come at me
		self.skus = {}
		self.directory = base_directory
		self.counter = 0
		
	def fetch_sku(self):
		self.cur.execute("SELECT product_id, SKU FROM icon_info")
		rows = self.cur.fetchall()
		for row in rows:
			#print "({},{})".format(row[0], row[1])
			self.skus[int(row[0])] = row[1]
			
	
	def sku_match(self, filename):
		for id, sku in self.skus.iteritems():
			if str(sku) in filename:
				#print id
				return [id, sku]
		return []
	
	def rename(self, sku, filename, id):
		#print isinstance(sku, str)
		new = filename.replace(sku, "WS-{}".format(id))
		#print "Renaming. Filename={}, ID={}, New={}, SKU={}".format(filename, id, new[0], self.skus[id])
		os.rename(str(filename), str(new))
			
	def run(self):
		self.fetch_sku()
		for root, dirs, files in os.walk(self.directory):
			for filename in files:
				self.counter = self.counter + 1
				if self.counter % 2000 == 0: # pregress report
					print "Status {}: {}".format(self.counter, filename)
				test = self.sku_match(filename)
				if test:
					try:
						self.rename(test[1], os.path.join(root, filename), test[0])
					except WindowsError:
						print "Error: {}:{}".format(test, filename)
if __name__ == '__main__':
	i = ImageSorter(os.getcwd())
	i.run()