EE: Remove dead MySQL code

ee/app/models/ee/epic.rb

@@ -52,10 +52,7 @@ module EE
       scope :inc_group, -> { includes(:group) }
 
       scope :order_start_or_end_date_asc, -> do
-        # mysql returns null values first in opposite to postgres which
-        # returns them last by default
-        nulls_first = ::Gitlab::Database.postgresql? ? 'NULLS FIRST' : ''
-        reorder("COALESCE(start_date, end_date) ASC #{nulls_first}")
+        reorder("COALESCE(start_date, end_date) ASC NULLS FIRST")
       end
 
       scope :order_start_date_asc, -> do
@@ -170,9 +167,6 @@ module EE
       end
 
       def update_start_and_due_dates(epics)
-        # In MySQL, we cannot use a subquery that references the table being updated
-        epics = epics.pluck(:id) if ::Gitlab::Database.mysql? && epics.is_a?(ActiveRecord::Relation)
-
         self.where(id: epics).update_all(
           [
             %{

ee/app/workers/clear_shared_runners_minutes_worker.rb

@@ -10,14 +10,11 @@ class ClearSharedRunnersMinutesWorker
   def perform
     return unless try_obtain_lease
 
-    if Gitlab::Database.postgresql?
-      # Using UPDATE with a joined table is not supported in MySql
-      Namespace.with_shared_runners_minutes_limit
-        .with_extra_shared_runners_minutes_limit
-        .where('namespace_statistics.namespace_id = namespaces.id')
-        .where('namespace_statistics.shared_runners_seconds > (namespaces.shared_runners_minutes_limit * 60)')
-        .update_all("extra_shared_runners_minutes_limit = #{extra_minutes_left_sql} FROM namespace_statistics")
-    end
+    Namespace.with_shared_runners_minutes_limit
+      .with_extra_shared_runners_minutes_limit
+      .where('namespace_statistics.namespace_id = namespaces.id')
+      .where('namespace_statistics.shared_runners_seconds > (namespaces.shared_runners_minutes_limit * 60)')
+      .update_all("extra_shared_runners_minutes_limit = #{extra_minutes_left_sql} FROM namespace_statistics")
 
     Namespace.where('last_ci_minutes_notification_at IS NOT NULL OR last_ci_minutes_usage_notification_level IS NOT NULL')
       .each_batch do |relation|

ee/lib/ee/gitlab/background_migration/rollback_import_state_data.rb

@@ -10,32 +10,18 @@ module EE
         def move_attributes_data_to_project(start_id, end_id)
           Rails.logger.info("#{self.class.name} - Moving import attributes data to projects table: #{start_id} - #{end_id}") # rubocop:disable Gitlab/RailsLogger
 
-          if ::Gitlab::Database.mysql?
-            ActiveRecord::Base.connection.execute <<~SQL
-              UPDATE projects, project_mirror_data
-              SET
-                projects.import_status = project_mirror_data.status,
-                projects.import_jid = project_mirror_data.jid,
-                projects.mirror_last_update_at = project_mirror_data.last_update_at,
-                projects.mirror_last_successful_update_at = project_mirror_data.last_successful_update_at,
-                projects.import_error = project_mirror_data.last_error
-              WHERE project_mirror_data.project_id = projects.id
-              AND project_mirror_data.id BETWEEN #{start_id} AND #{end_id}
-            SQL
-          else
-            ActiveRecord::Base.connection.execute <<~SQL
-              UPDATE projects
-              SET
-                import_status = project_mirror_data.status,
-                import_jid = project_mirror_data.jid,
-                mirror_last_update_at = project_mirror_data.last_update_at,
-                mirror_last_successful_update_at = project_mirror_data.last_successful_update_at,
-                import_error = project_mirror_data.last_error
-              FROM project_mirror_data
-              WHERE project_mirror_data.project_id = projects.id
-              AND project_mirror_data.id BETWEEN #{start_id} AND #{end_id}
-            SQL
-          end
+          ActiveRecord::Base.connection.execute <<~SQL
+            UPDATE projects
+            SET
+              import_status = project_mirror_data.status,
+              import_jid = project_mirror_data.jid,
+              mirror_last_update_at = project_mirror_data.last_update_at,
+              mirror_last_successful_update_at = project_mirror_data.last_successful_update_at,
+              import_error = project_mirror_data.last_error
+            FROM project_mirror_data
+            WHERE project_mirror_data.project_id = projects.id
+            AND project_mirror_data.id BETWEEN #{start_id} AND #{end_id}
+          SQL
         end
       end
     end

ee/lib/ee/gitlab/database.rb

@@ -14,8 +14,6 @@ module EE
         end
 
         def healthy?
-          return true unless postgresql?
-
           !Postgresql::ReplicationSlot.lag_too_great?
         end
 

ee/lib/gitlab/geo.rb

@@ -29,7 +29,7 @@ module Gitlab
     end
 
     def self.connected?
-      Gitlab::Database.postgresql? && GeoNode.connected? && GeoNode.table_exists?
+      GeoNode.connected? && GeoNode.table_exists?
     end
 
     def self.enabled?

ee/spec/lib/ee/gitlab/database_spec.rb

@@ -35,28 +35,16 @@ describe Gitlab::Database do
   end
 
   describe '.healthy?' do
-    it 'returns true when using MySQL' do
-      allow(described_class).to receive(:postgresql?).and_return(false)
+    it 'returns true when replication lag is not too great' do
+      allow(Postgresql::ReplicationSlot).to receive(:lag_too_great?).and_return(false)
 
       expect(described_class.healthy?).to be_truthy
     end
 
-    context 'when using PostgreSQL' do
-      before do
-        allow(described_class).to receive(:postgresql?).and_return(true)
-      end
+    it 'returns false when replication lag is too great' do
+      allow(Postgresql::ReplicationSlot).to receive(:lag_too_great?).and_return(true)
 
-      it 'returns true when replication lag is not too great' do
-        allow(Postgresql::ReplicationSlot).to receive(:lag_too_great?).and_return(false)
-
-        expect(described_class.healthy?).to be_truthy
-      end
-
-      it 'returns false when replication lag is too great' do
-        allow(Postgresql::ReplicationSlot).to receive(:lag_too_great?).and_return(true)
-
-        expect(described_class.healthy?).to be_falsey
-      end
+      expect(described_class.healthy?).to be_falsey
     end
   end
 

ee/spec/lib/gitlab/geo_spec.rb

@@ -138,12 +138,6 @@ describe Gitlab::Geo, :geo, :request_store do
 
         expect(described_class.connected?).to be_falsey
       end
-
-      it 'returns false when MySQL is in use' do
-        allow(Gitlab::Database).to receive(:postgresql?) { false }
-
-        expect(described_class.connected?).to be_falsey
-      end
     end
   end