Switch to using a boolean

Update migrations and schema
Update code and specs

db/migrate/20210222030537_add_removed_at_to_oncall_participant.rb

@@ -7,13 +7,11 @@ class AddRemovedAtToOncallParticipant < ActiveRecord::Migration[6.0]
 
   def up
     with_lock_retries do
-      add_column :incident_management_oncall_participants, :removed_at, :datetime_with_timezone
+      add_column :incident_management_oncall_participants, :is_removed, :boolean, default: false
     end
   end
 
   def down
-    remove_column :incident_management_oncall_participants, :removed_at
+    remove_column :incident_management_oncall_participants, :is_removed
   end
 end
-
-

db/migrate/20210222042745_add_removed_at_to_oncall_participant_index.rb

@@ -3,14 +3,16 @@
 class AddRemovedAtToOncallParticipantIndex < ActiveRecord::Migration[6.0]
   include Gitlab::Database::MigrationHelpers
 
-  DOWNTIME = false
   disable_ddl_transaction!
 
+  DOWNTIME = false
+  INDEX_NAME = 'index_incident_management_oncall_participants_is_removed'
+
   def up
-    add_concurrent_index :incident_management_oncall_participants, :removed_at
+    add_concurrent_index :incident_management_oncall_participants, :is_removed, name: INDEX_NAME
   end
 
   def down
-    remove_concurrent_index :incident_management_oncall_participants, :removed_at
+    remove_concurrent_index_by_name(:incident_management_oncall_participants, INDEX_NAME)
   end
 end

db/structure.sql

@@ -13234,7 +13234,7 @@ CREATE TABLE incident_management_oncall_participants (
     user_id bigint NOT NULL,
     color_palette smallint NOT NULL,
     color_weight smallint NOT NULL,
-    removed_at timestamp with time zone
+    is_removed boolean DEFAULT false
 );
 
 CREATE SEQUENCE incident_management_oncall_participants_id_seq
@@ -22461,7 +22461,7 @@ CREATE UNIQUE INDEX index_inc_mgmnt_oncall_rotations_on_oncall_schedule_id_and_n
 CREATE INDEX index_incident_management_oncall_schedules_on_project_id ON incident_management_oncall_schedules USING btree (project_id);
 
 CREATE INDEX index_incident_management_oncall_shifts_on_participant_id ON incident_management_oncall_shifts USING btree (participant_id);
-CREATE INDEX index_incident_management_oncall_participants_on_removed_at ON incident_management_oncall_participants USING btree (removed_at);
+CREATE INDEX index_incident_management_oncall_participants_is_removed ON incident_management_oncall_participants USING btree (is_removed);
 
 CREATE UNIQUE INDEX index_index_statuses_on_project_id ON index_statuses USING btree (project_id);
 

ee/app/models/incident_management/oncall_participant.rb

@@ -21,11 +21,11 @@ module IncidentManagement
 
     delegate :project, to: :rotation, allow_nil: true
 
-    scope :not_removed, -> { where(removed_at: nil) }
-    scope :removed, -> { where('removed_at is NOT NULL') }
+    scope :not_removed, -> { where(is_removed: false) }
+    scope :removed, -> { where(is_removed: true) }
 
     def mark_as_removed
-      update_column(:removed_at, Time.current)
+      update_column(:is_removed, true)
     end
   end
 end

ee/spec/factories/incident_management/oncall_participant.rb

@@ -14,7 +14,7 @@ FactoryBot.define do
     end
 
     trait :removed do
-      removed_at { Time.current }
+      is_removed { true }
     end
   end
 end

ee/spec/models/incident_management/oncall_participant_spec.rb

@@ -62,8 +62,8 @@ RSpec.describe IncidentManagement::OncallParticipant do
 
     subject { participant.mark_as_removed }
 
-    it 'updates removed_at to the current time' do
-      expect { subject }.to change { participant.reload.removed_at }.to(Time.current)
+    it 'updates is_removed to the current time' do
+      expect { subject }.to change { participant.reload.is_removed }.to(true)
     end
   end