ruby on rails - Reducing the number of queries kaminari makes -

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given following code:

# items_controller class itemscontroller < applicationcontroller   def show     @files = @item.essences.page(params[:files_page]).per(params[:files_per_page])   end end

and

# items/_essences.html.haml  = paginate @files, :param_name => :files_page  %table.table   %thead     %tr       = sortable :foo       = sortable :bar       = sortable :baz       = sortable :aaa       %th blah   %tbody     - if @files.empty?       %tr         %td no files available         %td         %td         %td         %td     - else       - @files.each |file|         %tr           %td= file.foo           %td= file.bar           %td= file.baz           %td= file.aaa           %td= blah       %tr         %td           %b== #{@files.count} files         %td== --         %td           %b= number_to_human_size @files.sum(&:size)         %td== --         %td== --  = paginate @files, :param_name => :files_page  %p   %button.per_page{:data => {:per => 10, :param_name => :files_per_page}} show 10   %button.per_page{:data => {:per => 50, :param_name => :files_per_page}} show 50   %button.per_page{:data => {:per => @num_files, :param_name => :files_per_page}} show

i'm looking through rack-mini-profiler , seeing sql queries getting generated

executing action: show t+2450.2 ms reader 1.1 ms app/controllers/items_controller.rb:72:in `show' select `essences`.* `essences`  `essences`.`item_id` = 729

and

rendering: items/_essences t+2991.6 ms reader 0.4 ms app/views/items/_essences.html.haml:2:in `_app_views_items__essences_html_haml__2548715375674979383_70349081205780' app/views/items/show.html.haml:157:in `_app_views_items_show_html_haml__802676714698420534_70349066386680' app/controllers/items_controller.rb:81:in `show' select count(*) `essences`  `essences`.`item_id` = 729

and

rendering: items/_essences t+3045.4 ms reader 0.6 ms app/views/items/_essences.html.haml:13:in `_app_views_items__essences_html_haml__2548715375674979383_70349081205780' app/views/items/show.html.haml:157:in `_app_views_items_show_html_haml__802676714698420534_70349066386680' app/controllers/items_controller.rb:81:in `show' select count(count_column) (select  1 count_column `essences`  `essences`.`item_id` = 729 limit 25 offset 0) subquery_for_count

and

rendering: items/_essences t+3049.4 ms reader 1.3 ms app/views/items/_essences.html.haml:21:in `_app_views_items__essences_html_haml__2548715375674979383_70349081205780' app/views/items/show.html.haml:157:in `_app_views_items_show_html_haml__802676714698420534_70349066386680' app/controllers/items_controller.rb:81:in `show' select  `essences`.* `essences`  `essences`.`item_id` = 729 limit 25 offset 0

looking @ results, there seem redundant sql calls.

after paginate @files, :param_name => :files_page call made, shouldn't number of pages available calculated, , therefore shouldn't known whether or not @files.empty? true or not?

is reason it's not calculated performance gained on avoiding sql call @files.empty? not worthwhile? (i'm new optimizing rails applications, maybe fact query takes 0.6ms means it's not worth worrying about)

i realize itemscontroller#show , @files.each both select essences.*, seems mistake on rails' application coder's part, not upon kaminari's part.

i'm using rails 3.2, , activerecord, , latest version of kaminari.


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