Implement review comments from @yorickpeterse

1. Change multiple updates to a single `update_all`

2. Use cascading deletes

3. Extract an average function for the database median.

4. Move database median to `lib/gitlab/database`

5. Use `delete_all` instead of `destroy_all`

6. Minor refactoring

1 files changed, 0 insertions, 80 deletions

diff --git a/app/models/cycle_analytics/queries.rb b/app/models/cycle_analytics/queries.rb
deleted file mode 100644
index 7bdf1fb6290..00000000000
--- a/app/models/cycle_analytics/queries.rb
+++ /dev/null
@@ -1,80 +0,0 @@
-class CycleAnalytics
-  class Queries
-    def initialize(project)
-      @project = project
-    end
-
-    def issues(options = {})
-      @issues_data ||=
-        begin
-          issues_query(options).preload(:metrics).map { |issue| { issue: issue } }
-        end
-    end
-
-    def merge_requests_closing_issues(options = {})
-      @merge_requests_closing_issues_data ||=
-        begin
-          merge_requests_closing_issues = MergeRequestsClosingIssues.where(issue: issues_query(options)).preload(issue: [:metrics], merge_request: [:metrics])
-
-          merge_requests_closing_issues.map do |record|
-            { issue: record.issue, merge_request: record.merge_request }
-          end
-        end
-    end
-
-    def issue_first_associated_with_milestone_at
-      lambda do |data_point|
-        issue = data_point[:issue]
-        issue.metrics.first_associated_with_milestone_at if issue.metrics.present?
-      end
-    end
-
-    def issue_first_added_to_list_label_at
-      lambda do |data_point|
-        issue = data_point[:issue]
-        issue.metrics.first_added_to_board_at if issue.metrics.present?
-      end
-    end
-
-    def issue_first_mentioned_in_commit_at
-      lambda do |data_point|
-        issue = data_point[:issue]
-        issue.metrics.first_mentioned_in_commit_at if issue.metrics.present?
-      end
-    end
-
-    def merge_request_merged_at
-      lambda do |data_point|
-        merge_request = data_point[:merge_request]
-        merge_request.metrics.merged_at if merge_request.metrics.present?
-      end
-    end
-
-    def merge_request_build_started_at
-      lambda do |data_point|
-        merge_request = data_point[:merge_request]
-        merge_request.metrics.latest_build_started_at if merge_request.metrics.present?
-      end
-    end
-
-    def merge_request_build_finished_at
-      lambda do |data_point|
-        merge_request = data_point[:merge_request]
-        merge_request.metrics.latest_build_finished_at if merge_request.metrics.present?
-      end
-    end
-
-    def merge_request_deployed_to_production_at
-      lambda do |data_point|
-        merge_request = data_point[:merge_request]
-        merge_request.metrics.first_deployed_to_production_at if merge_request.metrics.present?
-      end
-    end
-
-    private
-
-    def issues_query(created_after:)
-      @project.issues.where("created_at >= ?", created_after)
-    end
-  end
-end