Optimize ci_builds counters for non MAU

Adds an index on name with type 'ci_build' to count non-MAU counters
in usage data

changelogs/unreleased/208884-optimize-ci_builds-counters-in-non-mau.yml

+---
+title: Optimize ci builds non distinct counters in usage data
+merge_request: 28027
+author:
+type: performance

db/migrate/20200325160952_add_index_on_name_type_eq_ci_build_to_ci_builds.rb

+# frozen_string_literal: true
+
+class AddIndexOnNameTypeEqCiBuildToCiBuilds < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  INDEX_NAME = 'index_ci_builds_on_name_and_security_type_eq_ci_build'
+
+  def up
+    add_concurrent_index :ci_builds, [:name, :id],
+                         name: INDEX_NAME,
+                         where: "((name)::text = ANY (ARRAY[('container_scanning'::character varying)::text, ('dast'::character varying)::text, ('dependency_scanning'::character varying)::text, ('license_management'::character varying)::text, ('sast'::character varying)::text, ('license_scanning'::character varying)::text])) AND ((type)::text = 'Ci::Build'::text)"
+  end
+
+  def down
+    remove_concurrent_index_by_name :ci_builds, INDEX_NAME
+  end
+end

db/structure.sql

@@ -8604,6 +8604,8 @@ CREATE INDEX index_ci_builds_on_commit_id_and_type_and_name_and_ref ON public.ci
 
 CREATE INDEX index_ci_builds_on_commit_id_and_type_and_ref ON public.ci_builds USING btree (commit_id, type, ref);
 
+CREATE INDEX index_ci_builds_on_name_and_security_type_eq_ci_build ON public.ci_builds USING btree (name, id) WHERE (((name)::text = ANY (ARRAY[('container_scanning'::character varying)::text, ('dast'::character varying)::text, ('dependency_scanning'::character varying)::text, ('license_management'::character varying)::text, ('sast'::character varying)::text, ('license_scanning'::character varying)::text])) AND ((type)::text = 'Ci::Build'::text));
+
 CREATE INDEX index_ci_builds_on_name_for_security_reports_values ON public.ci_builds USING btree (name) WHERE ((name)::text = ANY (ARRAY[('container_scanning'::character varying)::text, ('dast'::character varying)::text, ('dependency_scanning'::character varying)::text, ('license_management'::character varying)::text, ('sast'::character varying)::text, ('license_scanning'::character varying)::text]));
 
 CREATE INDEX index_ci_builds_on_project_id_and_id ON public.ci_builds USING btree (project_id, id);
@@ -12807,5 +12809,6 @@ COPY "schema_migrations" (version) FROM STDIN;
 20200323122201
 20200323134519
 20200324115359
+20200325160952
 \.