Restrict cycle analytics usage data to instances that use postgres only

app/models/cycle_analytics.rb

@@ -7,13 +7,8 @@ class CycleAnalytics
   end
   def all_medians_per_stage
-    medians_per_stage = {}
-
-    # We only need this data for Postgres instances
-    return medians_per_stage if Gitlab::Database.mysql?
-
-    STAGES.each do |stage_name|
-      medians_per_stage[stage_name] = self[stage_name].median
+    STAGES.each_with_object({}) do |stage_name, hsh|
+      hsh[stage_name] = self[stage_name].median
     end
   end

lib/gitlab/cycle_analytics/base_query.rb

@@ -8,14 +8,14 @@ module Gitlab
       private
       def base_query
-        @base_query ||= stage_query([@project.id])
+        @base_query ||= stage_query([@project.id]) # rubocop:disable Gitlab/ModuleWithInstanceVariables
       end
       def stage_query(project_ids)
         query = mr_closing_issues_table.join(issue_table).on(issue_table[:id].eq(mr_closing_issues_table[:issue_id]))
           .join(issue_metrics_table).on(issue_table[:id].eq(issue_metrics_table[:issue_id]))
           .project(issue_table[:project_id].as("project_id"))
-          .where(issue_table[:project_id].in(project_ids)) # rubocop:disable Gitlab/ModuleWithInstanceVariables
+          .where(issue_table[:project_id].in(project_ids))
           .where(issue_table[:created_at].gteq(@options[:from])) # rubocop:disable Gitlab/ModuleWithInstanceVariables
         # Load merge_requests

lib/gitlab/usage_data.rb

@@ -73,6 +73,9 @@ module Gitlab
       end
       def cycle_analytics_usage_data
+        # We only want to generate this data for instances that use PostgreSQL
+        return {} if Gitlab::Database.mysql?
+
         projects = Project.sorted_by_activity.limit(Gitlab::CycleAnalytics::UsageData::PROJECTS_LIMIT)
         Gitlab::CycleAnalytics::UsageData.new(projects, { from: 7.days.ago }).to_json

spec/lib/gitlab/usage_data_spec.rb

@@ -36,6 +36,7 @@ describe Gitlab::UsageData do
         gitlab_shared_runners
         git
         database
+        avg_cycle_analytics
       ))
     end

spec/support/cycle_analytics_helpers/test_generation.rb

@@ -50,7 +50,7 @@ module CycleAnalyticsHelpers
               end
               median_time_difference = time_differences.sort[2]
-              expect(subject[phase].median).to be_within(5).of(median_time_difference)
+              expect(subject[phase].median.presence).to be_within(5).of(median_time_difference)
             end
             context "when the data belongs to another project" do