Rails 3.1 Identity Map issues?

Question

Does anyone know the key issues that the Rails 3.1 IdentityMap feature has that has forced the feature to be disabled by default? I\'m sure that there are minor specific iss

Answer 1

From the comments in the code:

# Active Record Identity Map does not track associations yet. For example:
#
# comment = @post.comments.first
# comment.post = nil
# @post.comments.include?(comment) #=> true
#
# Ideally, the example above would return false, removing the comment object from the
# post association when the association is nullified. This may cause side effects, as
# in the situation below, if Identity Map is enabled:
#
# Post.has_many :comments, :dependent => :destroy
#
# comment = @post.comments.first
# comment.post = nil
# comment.save
# Post.destroy(@post.id)
#
# Without using Identity Map, the code above will destroy the @post object leaving
# the comment object intact. However, once we enable Identity Map, the post loaded
# by Post.destroy is exactly the same object as the object @post. As the object @post
# still has the comment object in @post.comments, once Identity Map is enabled, the
# comment object will be accidently removed.
#
# This inconsistency is meant to be fixed in future Rails releases.