Methods
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Attributes
[R] query_cache
[R] query_cache_enabled
Class Public methods
dirties_query_cache(base, *method_names)
# File activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb, line 14
        def dirties_query_cache(base, *method_names)
          method_names.each do |method_name|
            base.class_eval "              def #{method_name}_with_query_dirty(*args)        # def update_with_query_dirty(*args)
                clear_query_cache if @query_cache_enabled       #   clear_query_cache if @query_cache_enabled
                #{method_name}_without_query_dirty(*args)       #   update_without_query_dirty(*args)
              end                                               # end
                                                                #
              alias_method_chain :#{method_name}, :query_dirty  # alias_method_chain :update, :query_dirty
", __FILE__, __LINE__ + 1
          end
        end
included(base)
# File activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb, line 5
def included(base)
  base.class_eval do
    alias_method_chain :columns, :query_cache
    alias_method_chain :select_all, :query_cache
  end
  dirties_query_cache base, :insert, :update, :delete
end
Instance Public methods
cache()

Enable the query cache within the block.

# File activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb, line 31
def cache
  old, @query_cache_enabled = @query_cache_enabled, true
  @query_cache ||= {}
  yield
ensure
  clear_query_cache
  @query_cache_enabled = old
end
clear_query_cache()

Clears the query cache.

One reason you may wish to call this method explicitly is between queries that ask the database to randomize results. Otherwise the cache would see the same SQL query and repeatedly return the same result each time, silently undermining the randomness you were expecting.

# File activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb, line 54
def clear_query_cache
  @query_cache.clear if @query_cache
end
columns_with_query_cache(*args)
# File activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb, line 66
def columns_with_query_cache(*args)
  if @query_cache_enabled
    @query_cache["SHOW FIELDS FROM #{args.first}"] ||= columns_without_query_cache(*args)
  else
    columns_without_query_cache(*args)
  end
end
select_all_with_query_cache(*args)
# File activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb, line 58
def select_all_with_query_cache(*args)
  if @query_cache_enabled
    cache_sql(args.first) { select_all_without_query_cache(*args) }
  else
    select_all_without_query_cache(*args)
  end
end
uncached()

Disable the query cache within the block.

# File activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb, line 41
def uncached
  old, @query_cache_enabled = @query_cache_enabled, false
  yield
ensure
  @query_cache_enabled = old
end