How do you disable AR query cache globally?

Rails
1

Ref my earlier post in this group regarding a problem with AR query
caching with MS SQL Server, I now find that the most convenient
solution would be simply disabling query caching globally for this
app.

Question is, how do you do that?

2

mh wrote:

Ref my earlier post in this group regarding a problem with AR query
caching with MS SQL Server, I now find that the most convenient
solution would be simply disabling query caching globally for this
app.

Question is, how do you do that?

all “global” settings should be in config/environment.rb or at least
loaded from there… while you are in that file, check out the comments
for a whole host of features that you can turn on and off (including
caching I believe)

hth

ilan

3

Ilan,

Thanks for your reply. Indeed, that’s exactly what one would expect:
to be able to set something in environment.rb (or in an environment-
specific file) such as:

config.active_record.query_cache_enabled = false

(That particular code fails with undefined method
`query_cache_enabled=’ for ActiveRecord::Base:Class.)

When you peruse the code that does the query results caching, you
might think you could setup an initializer that does the following:

ActiveRecord::Base.connection.query_cache_enabled = false

Unfortunately, that also doesn’t work, because ActiveController
actually explicitly enables the query cache when calling an action in
action_controller/caching.rb:

module ActionController #:nodoc:

…

Note: To turn off all caching and sweeping, set

Base.perform_caching = false.
module Caching
def self.included(base) #:nodoc:
base.class_eval do
include Pages, Actions, Fragments

    if defined? ActiveRecord
      include Sweeping, SqlCache
    end

    @@perform_caching = true
    cattr_accessor :perform_caching
  end
end ...

Where SqlCache looks like:

module SqlCache
  def self.included(base) #:nodoc:
    if defined?(ActiveRecord) && ActiveRecord::Base.respond_to?

(:cache)
base.alias_method_chain :perform_action, :caching
end
end

  def perform_action_with_caching
    ActiveRecord::Base.cache do
      perform_action_without_caching
    end
  end
end

It’s the ActiveRecord::Base.cache call that explicitly turns on query
caching that was the remaining culprit for me.

Consequently, given no apparent alternative other than to turn off ALL
caching using ActionController::Base.perform_caching = false, I have
disincluded SqlCache from being included in my controller, and that
has effectively disabled query caching. It appears there is no
convenient way to selectively disable just query caching while
maintaining the other sorts of caching that Rails does for you. If
someone else has a Better Way ™, please advise.

Michael

On Mar 17, 7:31 pm, Ilan B. [email protected]

4

It’s the ActiveRecord::Base.cache call that explicitly turns on query
caching that was the remaining culprit for me.

Michael

On Mar 17, 7:31�pm, Ilan B. [email protected]

Michael,
Would it be possible to open up the ActiveRecord::Base and
alias_method_chain the query caching methods to return nil or empty sets
which will effectively “disable it”?

I usually do my monkey patching in /lib and then load them up in
config/environment.rb…

Thanks for taking the time to explain it fully to me… was a very
interesting read…

good luck and keep me informed…

ilan