def rename(filter, source_uri, target_uri=nil, &each_key)
target_uri ||= source_uri
move_keys filter, source_uri, target_uri if source_uri != target_uri
source_keys = Familia.redis(source_uri).keys(filter)
puts "Renaming #{source_keys.size} keys from #{source_uri} (filter: #{filter})"
source_keys.each_with_index do |key,idx|
Familia.trace :RENAME1, Familia.redis(source_uri), "#{key}", ''
type = Familia.redis(source_uri).type key
ttl = Familia.redis(source_uri).ttl key
newkey = each_key.call(idx, type, key, ttl) unless each_key.nil?
Familia.trace :RENAME2, Familia.redis(source_uri), "#{key} -> #{newkey}", caller[0]
ret = Familia.redis(source_uri).renamenx key, newkey
end
end