Harden ci pipelines usage data with config sources

ci pipelines with auto_devops and config_repository config_source are
optimimized

changelogs/unreleased/223714-harden-ci-pipelines-auto_devops-config_repository-usage-data.yml

+---
+title: Rework hardening CI pipelines usage data queries with an index
+merge_request: 35494
+author:
+type: performance

db/post_migrate/20200704143633_add_index_on_user_id_and_created_at_where_source_to_ci_pipelines.rb

+# frozen_string_literal: true
+
+class AddIndexOnUserIdAndCreatedAtWhereSourceToCiPipelines < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :ci_pipelines, [:user_id, :created_at, :config_source]
+  end
+
+  def down
+    remove_concurrent_index :ci_pipelines, [:user_id, :created_at, :config_source]
+  end
+end

db/structure.sql

@@ -18764,6 +18764,8 @@ CREATE INDEX index_ci_pipelines_on_project_idandrefandiddesc ON public.ci_pipeli
 
 CREATE INDEX index_ci_pipelines_on_status ON public.ci_pipelines USING btree (status);
 
+CREATE INDEX index_ci_pipelines_on_user_id_and_created_at_and_config_source ON public.ci_pipelines USING btree (user_id, created_at, config_source);
+
 CREATE INDEX index_ci_pipelines_on_user_id_and_created_at_and_source ON public.ci_pipelines USING btree (user_id, created_at, source);
 
 CREATE UNIQUE INDEX index_ci_refs_on_project_id_and_ref_path ON public.ci_refs USING btree (project_id, ref_path);
@@ -23573,6 +23575,7 @@ COPY "schema_migrations" (version) FROM STDIN;
 20200630110826
 20200702123805
 20200703154822
+20200704143633
 20200706005325
 \.