Remove unnecessary index

db/migrate/20210429032320_add_escalation_rules.rb

@@ -3,13 +3,12 @@
 class AddEscalationRules < ActiveRecord::Migration[6.0]
   include Gitlab::Database::MigrationHelpers
 
-  RULE_POLICY_INDEX_NAME = 'index_on_project_escalation_rule'
   RULE_SCHEDULE_INDEX_NAME = 'index_on_oncall_schedule_escalation_rule'
   UNIQUENESS_INDEX_NAME = 'index_on_policy_schedule_status_elapsed_time_escalation_rules'
 
   def change
     create_table :incident_management_escalation_rules do |t|
-      t.belongs_to :policy, index: { name: RULE_POLICY_INDEX_NAME }, null: false, foreign_key: { on_delete: :cascade, to_table: :incident_management_escalation_policies }
+      t.belongs_to :policy, index: false, null: false, foreign_key: { on_delete: :cascade, to_table: :incident_management_escalation_policies }
       t.belongs_to :oncall_schedule, index: { name: RULE_SCHEDULE_INDEX_NAME }, null: false, foreign_key: { on_delete: :cascade, to_table: :incident_management_oncall_schedules }
       t.integer :status, null: false, limit: 2
       t.integer :elapsed_time_seconds, null: false, limit: 4

db/structure.sql

@@ -23614,8 +23614,6 @@ CREATE INDEX index_on_pages_metadata_not_migrated ON project_pages_metadata USIN
 
 CREATE UNIQUE INDEX index_on_policy_schedule_status_elapsed_time_escalation_rules ON incident_management_escalation_rules USING btree (policy_id, oncall_schedule_id, status, elapsed_time_seconds);
 
-CREATE INDEX index_on_project_escalation_rule ON incident_management_escalation_rules USING btree (policy_id);
-
 CREATE UNIQUE INDEX index_on_project_id_escalation_policy_name_unique ON incident_management_escalation_policies USING btree (project_id, name);
 
 CREATE INDEX index_on_projects_lower_path ON projects USING btree (lower((path)::text));