gistfile1.rb

## assume a flushed memcache database

## and Sport.rb which has a cache-money index on :name

class Sport < ActiveRecord::Base

  is_cached :repository => $cache
  
   # This configuration enables calls to Sport.find_by_name("baseball") to come from and be written to a cache
  index :name

end

## Let's try it

Sport.find_by_name("baseball")

## EXPECTED RESULT: SQL CALL: SELECT * FROM `sports` WHERE (`sports`.`name` = 'baseball')
## RESULT:          SQL CALL: SELECT * FROM `sports` WHERE (`sports`.`name` = 'baseball')

# Cache is cold, so this is expected
# Second attempt

Sport.find_by_name("baseball")

## EXPECTED RESULT: NO SQL CALL (from cache)
## RESULT:          SQL CALL: SELECT * FROM `sports` WHERE (`sports`.`id` = 49 AND (`sports`.`name` = 'baseball')) LIMIT 1

# Calls to Sport.find_by_name are not coming from the cache, even though we defined a cache money index for name.
# In fact, successive calls to find_by_name will do a memcache read but NEVER come from the cache ... UNLESS:

Sport.find(49) # the id of baseball
Sport.find_by_name("baseball")

## RESULT: NO SQL CALL (from cache)
## We've primed the result of the primary key finder into memcache and now successive calls to an indexed column will come out of the cache