diff --git a/.codeclimate.yml b/.codeclimate.yml
index ffcd2856cf..3869f2a950 100644
--- a/.codeclimate.yml
+++ b/.codeclimate.yml
@@ -31,7 +31,7 @@ plugins:
         enabled: false
   rubocop:
     enabled: true
-    channel: rubocop-1-18-3
+    channel: rubocop-1-45
     checks:
       Rubocop/Style/ClassAndModuleChildren:
         enabled: false
diff --git a/app/controllers/repp/v1/stats_controller.rb b/app/controllers/repp/v1/stats_controller.rb
index 052cdcbc45..b8c3b053fc 100644
--- a/app/controllers/repp/v1/stats_controller.rb
+++ b/app/controllers/repp/v1/stats_controller.rb
@@ -9,7 +9,7 @@ class StatsController < BaseController # rubocop:disable Metrics/ClassLength
         param :end_date, String, required: true, desc: 'Period end date'
       end
       def market_share_distribution
-        domains_by_rar = domains_by_registrar(@date_to, @date_from)
+        domains_by_rar = domains_by_registrar(@date_to)
         result = serialize_distribution_result(domains_by_rar)
         render_success(data: result)
       end
@@ -22,8 +22,8 @@ def market_share_distribution
         param :compare_to_end_date, String, required: true, desc: 'Comparison date'
       end
       def market_share_growth_rate
-        domains_by_rar = domains_by_registrar(@date_to, @date_from)
-        prev_domains_by_rar = domains_by_registrar(@date_compare_to, @date_compare_from)
+        domains_by_rar = domains_by_registrar(@date_to)
+        prev_domains_by_rar = domains_by_registrar(@date_compare_to)
 
         set_zero_values!(domains_by_rar, prev_domains_by_rar)
 
@@ -36,6 +36,7 @@ def market_share_growth_rate
                    data: { name: search_params[:end_date],
                            domains: serialize_growth_rate_result(domains_by_rar),
                            market_share: serialize_growth_rate_result(market_share_by_rar) } }
+
         render_success(data: result)
       end
       # rubocop:enable Metrics/MethodLength
@@ -43,15 +44,13 @@ def market_share_growth_rate
       private
 
       def search_params
-        params.permit(:q, q: %i[start_date end_date compare_to_end_date compare_to_start_date])
+        params.permit(:q, q: %i[end_date compare_to_end_date])
               .fetch(:q, {}) || {}
       end
 
       def set_date_params
         @date_to = to_date(search_params[:end_date]).end_of_month
-        @date_from = to_date(search_params[:start_date] || '01.05')
         @date_compare_to = to_date(search_params[:compare_to_end_date]).end_of_month
-        @date_compare_from = to_date(search_params[:compare_to_start_date] || '01.05')
       end
 
       def to_date(date_param)
@@ -78,35 +77,108 @@ def calculate_market_share(domains_by_rar)
         end
       end
 
-      def domains_by_registrar(date_to, date_from)
-        log_domains_del = log_domains(event: 'destroy', date_to: date_to, date_from: date_from)
-        log_domains_trans = log_domains(event: 'update', date_to: date_to, date_from: date_from)
-        logged_domains = log_domains_trans.map { |ld| ld.object['name'] } +
-                         log_domains_del.map { |ld| ld.object['name'] }
-        domains_grouped = ::Domain.where('created_at <= ? AND created_at >= ?', date_to, date_from)
-                                  .where.not(name: logged_domains.uniq)
-                                  .group(:registrar_id).count.stringify_keys
-        summarize([group(log_domains_del), group(log_domains_trans), domains_grouped])
-      end
-
-      def summarize(arr)
-        arr.inject { |memo, el| memo.merge(el) { |_, old_v, new_v| old_v + new_v } }
-      end
-
-      def log_domains(event:, date_to:, date_from:)
-        domains = ::Version::DomainVersion.where(event: event)
-        domains.where!("object_changes ->> 'registrar_id' IS NOT NULL") if event == 'update'
-        domains.where('created_at > ?', date_to)
-               .where("object ->> 'created_at' <= ?", date_to)
-               .where("object ->> 'created_at' >= ?", date_from)
-               .select("DISTINCT ON (object ->> 'name') object, created_at")
-               .order(Arel.sql("object ->> 'name', created_at desc"))
-      end
-
-      def group(domains)
-        domains.group_by { |ld| ld.object['registrar_id'].to_s }
-               .transform_values(&:count)
+      # rubocop:disable Metrics/MethodLength
+      def domains_by_registrar(date_to)
+        sql = <<-SQL
+          SELECT
+            registrar_id,
+            SUM(domain_count) AS total_domain_count
+          FROM (
+            -- Query for current domains for each registrar
+            SELECT
+              registrar_id::text AS registrar_id,
+              COUNT(*) AS domain_count
+            FROM
+              domains
+            GROUP BY
+              registrar_id
+
+            UNION ALL
+
+            -- Query for 'create' events and count domains created by registrar
+            SELECT
+              (object_changes->'registrar_id'->>1)::text AS registrar_id,
+              COUNT(*) * -1 AS domain_count
+            FROM
+              log_domains
+            WHERE
+              event = 'create'
+              AND created_at > :date_to
+            GROUP BY
+              registrar_id
+
+            UNION ALL
+
+            -- Query for 'update' events and count domains transferred to a new registrar
+            SELECT
+              (object_changes->'registrar_id'->>1)::text AS registrar_id,
+              COUNT(*) * -1 AS domain_count
+            FROM
+              log_domains
+            WHERE
+              event = 'update'
+              AND object_changes->'registrar_id' IS NOT NULL
+              AND created_at > :date_to
+            GROUP BY
+              registrar_id
+
+            UNION ALL
+
+            -- Query for 'update' events and count domains transferred from an old registrar
+            SELECT
+              (object_changes->'registrar_id'->>0)::text AS registrar_id,
+              COUNT(*) AS domain_count
+            FROM
+              log_domains
+            WHERE
+              event = 'update'
+              AND object_changes->'registrar_id' IS NOT NULL
+              AND created_at > :date_to
+            GROUP BY
+              registrar_id
+
+            UNION ALL
+
+            -- Query for 'destroy' events and count the number of domains destroyed associated with each registrar
+            SELECT
+              (object_changes->'registrar_id'->>0)::text AS registrar_id,
+              COUNT(*) AS domain_count
+            FROM
+                log_domains
+            WHERE
+                event = 'destroy'
+                AND object_changes->'registrar_id' IS NOT NULL
+                AND created_at > :date_to
+            GROUP BY
+                registrar_id
+
+            UNION ALL
+
+            -- Query for 'destroy' events and count the number of domains destroyed associated with each registrar
+            SELECT
+              (object->'registrar_id')::text AS registrar_id,
+              COUNT(*) AS domain_count
+            FROM
+                log_domains
+            WHERE
+                event = 'destroy'
+                AND object_changes IS NULL
+                AND created_at > :date_to
+            GROUP BY
+                registrar_id
+
+          ) AS combined
+          GROUP BY
+            registrar_id;
+        SQL
+
+        ActiveRecord::Base.connection.execute(
+          ActiveRecord::Base.send(:sanitize_sql_array, [sql, { date_to: date_to }])
+        ).each_with_object({}) do |row, hash|
+          hash[row['registrar_id']] = row['total_domain_count'].to_i
+        end
       end
+      # rubocop:enable Metrics/MethodLength
 
       def registrar_names
         @registrar_names ||= ::Registrar.where(test_registrar: false)
@@ -120,7 +192,10 @@ def serialize_distribution_result(result)
 
           name = registrar_names[key]
           hash = { name: name, y: value }
-          hash.merge!({ sliced: true, selected: true }) if current_user.registrar.name == name
+          if current_user.registrar.name == name
+            hash[:sliced] = true
+            hash[:selected] = true
+          end
           hash
         end.compact
       end
diff --git a/test/fixtures/domains.yml b/test/fixtures/domains.yml
index 01c43d644d..770559bdf0 100644
--- a/test/fixtures/domains.yml
+++ b/test/fixtures/domains.yml
@@ -12,7 +12,7 @@ shop:
   period: 1
   period_unit: m
   uuid: 1b3ee442-e8fe-4922-9492-8fcb9dccc69c
-  created_at: <%= 2.days.ago.to_s :db %>
+  created_at: <%= 2.months.ago.to_s :db %>
 
 airport:
   name: airport.test
@@ -51,7 +51,7 @@ metro:
   period: 1
   period_unit: m
   uuid: ef97cb80-333b-4893-b9df-163f2b452798
-  created_at: <%= 2.days.ago.to_s :db %>
+  created_at: <%= 3.months.ago.to_s :db %>
 
 hospital:
   name: hospital.test
diff --git a/test/fixtures/files/domain_versions.csv b/test/fixtures/files/domain_versions.csv
index 8fa7fa9fe8..52492e1539 100644
--- a/test/fixtures/files/domain_versions.csv
+++ b/test/fixtures/files/domain_versions.csv
@@ -1,3 +1,12 @@
 Name,Registrant,Registrar,Action,Created at
+,John,,destroy,2023-12-04 22:00:00
+hospital.test,John,Good Names,create,2023-12-04 22:00:00
+library.test,Acme Ltd,Best Names,create,2023-12-04 22:00:00
+shop.test,John,Best Names,update,2023-12-04 22:00:00
+invalid.test,any,Best Names,create,2023-12-04 22:00:00
+airport.test,John,Best Names,create,2023-12-04 22:00:00
+shop.test,John,Good Names,create,2023-10-04 21:00:00
+cinema.test,John,Good Names,create,2023-09-04 21:00:00
+metro.test,Jack,Good Names,create,2023-09-04 21:00:00
 ,test_code,Best Names,update,2018-04-23 15:50:48
 ,John,,update,2010-07-04 21:00:00
diff --git a/test/fixtures/log_domains.yml b/test/fixtures/log_domains.yml
index f328f902a6..bbd161c64e 100644
--- a/test/fixtures/log_domains.yml
+++ b/test/fixtures/log_domains.yml
@@ -5,4 +5,96 @@ one:
   object:
     registrant_id: <%= ActiveRecord::FixtureSet.identify(:john) %>
     updated_at: <%= Time.zone.parse('2010-07-05') %>
-  created_at: <%= Time.zone.parse('2010-07-05') %>
\ No newline at end of file
+  created_at: <%= Time.zone.parse('2010-07-05') %>
+
+create_one:
+  item_id: <%= ActiveRecord::FixtureSet.identify(:shop) %>
+  item_type: Domain
+  event: create
+  object_changes:
+    name: [null, 'shop.test']
+    registrar_id: [null, <%= ActiveRecord::FixtureSet.identify(:goodnames) %>]
+    registrant_id: [null, <%= ActiveRecord::FixtureSet.identify(:john) %>]
+  created_at: <%= Time.zone.parse('2023-10-05') %>
+
+create_two:
+  item_id: <%= ActiveRecord::FixtureSet.identify(:airport) %>
+  item_type: Domain
+  event: create
+  object_changes:
+    name: [null, 'airport.test']
+    registrar_id: [null, <%= ActiveRecord::FixtureSet.identify(:bestnames) %>]
+    registrant_id: [null, <%= ActiveRecord::FixtureSet.identify(:john) %>]
+  created_at: <%= Time.zone.parse('2023-12-05') %>
+
+create_three:
+  item_id: <%= ActiveRecord::FixtureSet.identify(:hospital) %>
+  item_type: Domain
+  event: create
+  object_changes:
+    name: [null, 'hospital.test']
+    registrar_id: [null, <%= ActiveRecord::FixtureSet.identify(:goodnames) %>]
+    registrant_id: [null, <%= ActiveRecord::FixtureSet.identify(:john) %>]
+  created_at: <%= Time.zone.parse('2023-12-05') %>
+
+create_four:
+  item_id: <%= ActiveRecord::FixtureSet.identify(:invalid) %>
+  item_type: Domain
+  event: create
+  object_changes:
+    name: [null, 'invalid.test']
+    registrar_id: [null, <%= ActiveRecord::FixtureSet.identify(:bestnames) %>]
+    registrant_id: [null, <%= ActiveRecord::FixtureSet.identify(:invalid) %>]
+  created_at: <%= Time.zone.parse('2023-12-05') %>
+
+transfer_one:
+  item_id: <%= ActiveRecord::FixtureSet.identify(:shop) %>
+  item_type: Domain
+  event: update
+  object: 
+    name: 'shop.test'
+    registrant_id: <%= ActiveRecord::FixtureSet.identify(:john) %>
+  object_changes:
+    registrar_id: [<%= ActiveRecord::FixtureSet.identify(:goodnames) %>, <%= ActiveRecord::FixtureSet.identify(:bestnames) %>]
+  created_at: <%= Time.zone.parse('2023-12-05') %>
+
+create_five:
+  item_id: 1111111
+  item_type: Domain
+  event: create
+  object_changes:
+    name: [null, 'cinema.test']
+    registrar_id: [null, <%= ActiveRecord::FixtureSet.identify(:goodnames) %>]
+    registrant_id: [null, <%= ActiveRecord::FixtureSet.identify(:john) %>]
+  created_at: <%= Time.zone.parse('2023-09-05') %>
+
+destroy_one:
+  item_id: 1111111
+  item_type: Domain
+  event: destroy
+  object:
+    registrant_id: <%= ActiveRecord::FixtureSet.identify(:john) %>
+  object_changes:
+    name: ['cinema.test', null]
+    registrar_id: [<%= ActiveRecord::FixtureSet.identify(:goodnames) %>, null]
+  created_at: <%= Time.zone.parse('2023-12-05') %>
+
+create_six:
+  item_id: <%= ActiveRecord::FixtureSet.identify(:library) %>
+  item_type: Domain
+  event: create
+  object_changes:
+    name: [null, 'library.test']
+    registrar_id: [null, <%= ActiveRecord::FixtureSet.identify(:bestnames) %>]
+    registrant_id: [null, <%= ActiveRecord::FixtureSet.identify(:acme_ltd) %>]
+  created_at: <%= Time.zone.parse('2023-12-05') %>
+
+create_seven:
+  item_id: <%= ActiveRecord::FixtureSet.identify(:metro) %>
+  item_type: Domain
+  event: create
+  object_changes:
+    name: [null, 'metro.test']
+    registrar_id: [null, <%= ActiveRecord::FixtureSet.identify(:goodnames) %>]
+    registrant_id: [null, <%= ActiveRecord::FixtureSet.identify(:jack) %>]
+  created_at: <%= Time.zone.parse('2023-09-05') %>
\ No newline at end of file
diff --git a/test/integration/repp/v1/stats/market_share_test.rb b/test/integration/repp/v1/stats/market_share_test.rb
index d3acba89b9..2f129d8439 100644
--- a/test/integration/repp/v1/stats/market_share_test.rb
+++ b/test/integration/repp/v1/stats/market_share_test.rb
@@ -19,8 +19,8 @@ def test_shows_market_share_distribution_data
     assert_equal 1000, json[:code]
     assert_equal 'Command completed successfully', json[:message]
 
-    assert json[:data].is_a? Array
-    assert json[:data][0].is_a? Hash
+    assert_equal json[:data], [{ name: 'Good Names', y: 2 },
+                               { name: @user.registrar.name, y: 4, sliced: true, selected: true }]
   end
 
   def test_shows_market_share_growth_rate_data
@@ -34,10 +34,11 @@ def test_shows_market_share_growth_rate_data
     assert_equal 1000, json[:code]
     assert_equal 'Command completed successfully', json[:message]
 
-    data = json[:data]
-    assert data[:data].is_a? Hash
-    assert data[:prev_data].is_a? Hash
-    assert_equal data[:data][:name], @today
-    assert data[:data][:domains].is_a? Array
+    assert_equal json[:data], prev_data: { name: prev_date,
+                                           domains: [['Good Names', 3], ['Best Names', 0]],
+                                           market_share: [['Good Names', 100.0], ['Best Names', 0.0]] },
+                              data: { name: @today,
+                                      domains: [['Good Names', 2], ['Best Names', 4]],
+                                      market_share: [['Good Names', 33.3], ['Best Names', 66.7]] }
   end
-end
\ No newline at end of file
+end
diff --git a/test/learning/paper_trail_test.rb b/test/learning/paper_trail_test.rb
index 9e116bf639..bd6c7993e0 100644
--- a/test/learning/paper_trail_test.rb
+++ b/test/learning/paper_trail_test.rb
@@ -24,13 +24,14 @@ def test_returns_version_list
 
   def test_returns_version_count_on_domains
     @domain = domains(:airport)
-    @domain.save
-
-    assert_equal 1, @domain.versions.count
+    assert_difference -> { @domain.versions.count }, 1 do
+      @domain.save
+    end
 
     @domain.name = 'domain.test'
-    @domain.save!
-    assert_equal 2, @domain.versions.count
+    assert_difference -> { @domain.versions.count }, 1 do
+      @domain.save!
+    end
   end
 
   def test_returns_version_count_on_users