Merge pull request #16014 from CartoDB/feature/ch123224/levinscott-very-slow-dashboard-loading

[ch123224] Optimize dashboard loading when the number of datasets is very large

NEWS.md

@@ -39,6 +39,7 @@ sudo make install
 - Bump version of lib/sql submodule to 0.37.1
 - Public profile can be disabled via Feature Flag [#15982](https://github.com/CartoDB/cartodb/pull/15995)
 - Migrate Organization CRUD to MessageBroker [#15934](https://github.com/CartoDB/cartodb/pull/15934)
+- Optimize dashboard loading when the number of datasets is very large [#16014](https://github.com/CartoDB/cartodb/pull/16014)
 
 4.44.0 (2020-11-20)
 -------------------

app/controllers/carto/api/visualizations_controller.rb

@@ -98,11 +98,10 @@ module Carto
             unless (params[:subscribed] == 'true' and not v.subscription.present?) or (params[:sample] == 'true' and not v.sample.present?)
         end.compact
 
-        total_subscriptions = 0
-        vqb.filtered_query.find_each{|v| total_subscriptions += 1 if v.subscription.present?}
-
-        total_samples = 0
-        vqb.filtered_query.find_each{|v| total_samples += 1 if v.sample.present?}
+        total_subscriptions = vqb.filtered_query.includes(map: { user_table: :data_import })
+                                 .find_each.lazy.count { |v| v.subscription.present? }
+        total_samples = vqb.filtered_query.includes(map: { user_table: :data_import })
+                           .find_each.lazy.count { |v| v.sample.present? }
 
         total_entries = vqb.count
         total_entries = total_subscriptions if params[:subscribed] == 'true'

app/models/carto/visualization.rb

@@ -667,18 +667,18 @@ class Carto::Visualization < ActiveRecord::Base
   end
 
   def subscription
-    table_name = (user_table.name if user_table) || (related_tables[0].name if related_tables && related_tables[0])
-    @subscription ||= if table_name
+    table = user_table || related_tables.try(:first)
+    @subscription ||= if table
       doss = Carto::DoSyncServiceFactory.get_for_user(user)
-      doss&.subscription_from_sync_table(table_name)
+      doss&.subscription_from_sync_table(table)
     end
   end
 
   def sample
-    table_name = (user_table.name if user_table) || (related_tables[0].name if related_tables && related_tables[0])
-    @sample ||= if table_name
+    table = user_table || related_tables.try(:first)
+    @sample ||= if table
       doss = Carto::DoSampleServiceFactory.get_for_user(user)
-      doss&.dataset_from_sample_table(table_name)
+      doss&.dataset_from_sample_table(table)
     end
   end