Merge branch 'improve-compliance-merge-request-query' into 'master'

Add index for compliance merged MRs to events

See merge request gitlab-org/gitlab!38885

changelogs/unreleased/improve-compliance-merge-request-query.yml

+---
+title: Add index for compliance merged MRs to events
+merge_request: 38885
+author:
+type: performance

db/migrate/20200807070820_add_index_for_compliance_merged_merge_request_to_events.rb

+# frozen_string_literal: true
+
+class AddIndexForComplianceMergedMergeRequestToEvents < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  INDEX_NAME = 'index_events_on_project_id_and_id_desc_on_merged_action'
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :events, [:project_id, :id],
+      order: { id: :desc },
+      where: "action = 7", name: INDEX_NAME
+  end
+
+  def down
+    remove_concurrent_index_by_name :events, INDEX_NAME
+  end
+end

db/schema_migrations/20200807070820

+a1fb6b5d486eee27aaed5083aa6340073bf05abab8f201fd9097374dbd345b90
\ No newline at end of file

db/structure.sql

@@ -19600,6 +19600,8 @@ CREATE INDEX index_events_on_project_id_and_created_at ON public.events USING bt
 
 CREATE INDEX index_events_on_project_id_and_id ON public.events USING btree (project_id, id);
 
+CREATE INDEX index_events_on_project_id_and_id_desc_on_merged_action ON public.events USING btree (project_id, id DESC) WHERE (action = 7);
+
 CREATE INDEX index_events_on_target_type_and_target_id ON public.events USING btree (target_type, target_id);
 
 CREATE UNIQUE INDEX index_events_on_target_type_and_target_id_and_fingerprint ON public.events USING btree (target_type, target_id, fingerprint);