Use full text search when searching issues

app/controllers/concerns/issuable_collections.rb

@@ -117,6 +117,10 @@ module IssuableCollections
         options[:attempt_group_search_optimizations] = true
       end
 
+      if collection_type == 'Issue' && Feature.enabled?(:issues_full_text_search, @project || @group, default_enabled: :yaml)
+        options[:attempt_full_text_search] = true
+      end
+
       params.permit(finder_type.valid_params).merge(options)
     end
   end

app/finders/issuable_finder.rb

@@ -37,6 +37,7 @@
 #     attempt_project_search_optimizations: boolean
 #     crm_contact_id: integer
 #     crm_organization_id: integer
+#     attempt_full_text_search: boolean
 #
 class IssuableFinder
   prepend FinderWithCrossProjectAccess
@@ -46,6 +47,7 @@ class IssuableFinder
 
   requires_cross_project_access unless: -> { params.project? }
 
+  FULL_TEXT_SEARCH_TERM_REGEX = /\A[\p{ASCII}|\p{Latin}]+\z/.freeze
   NEGATABLE_PARAMS_HELPER_KEYS = %i[project_id scope status include_subgroups].freeze
 
   attr_accessor :current_user, :params
@@ -331,6 +333,8 @@ class IssuableFinder
     return items if items.is_a?(ActiveRecord::NullRelation)
     return items if Feature.enabled?(:disable_anonymous_search, type: :ops) && current_user.nil?
 
+    return items.pg_full_text_search(search) if use_full_text_search?
+
     if use_cte_for_search?
       cte = Gitlab::SQL::CTE.new(klass.table_name, items)
 
@@ -341,6 +345,10 @@ class IssuableFinder
   end
   # rubocop: enable CodeReuse/ActiveRecord
 
+  def use_full_text_search?
+    params[:attempt_full_text_search] && params[:search] =~ FULL_TEXT_SEARCH_TERM_REGEX
+  end
+
   # rubocop: disable CodeReuse/ActiveRecord
   def by_iids(items)
     params[:iids].present? ? items.where(iid: params[:iids]) : items

app/models/concerns/pg_full_text_searchable.rb

@@ -13,9 +13,9 @@
 # This module sets up an after_commit hook that updates the search data
 # when the searchable columns are changed.
 #
-# This also adds a `full_text_search` scope so you can do:
+# This also adds a `pg_full_text_search` scope so you can do:
 #
-# Model.full_text_search("some search term")
+# Model.pg_full_text_search("some search term")
 
 module PgFullTextSearchable
   extend ActiveSupport::Concern
@@ -82,5 +82,20 @@ module PgFullTextSearchable
         update_search_data!
       end
     end
+
+    def pg_full_text_search(search_term)
+      search_data_table = reflect_on_association(:search_data).klass.arel_table
+
+      joins(:search_data).where(
+        Arel::Nodes::InfixOperation.new(
+          '@@',
+          search_data_table[:search_vector],
+          Arel::Nodes::NamedFunction.new(
+            'websearch_to_tsquery',
+            [Arel::Nodes.build_quoted(TEXT_SEARCH_DICTIONARY), Arel::Nodes.build_quoted(search_term)]
+          )
+        )
+      )
+    end
   end
 end

config/feature_flags/development/issues_full_text_search.yml

+---
+name: issues_full_text_search
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/71913
+rollout_issue_url: 
+milestone: '14.5'
+type: development
+group: group::project management
+default_enabled: false

lib/gitlab/issuables_count_for_state.rb

@@ -144,7 +144,7 @@ module Gitlab
     def params_include_filters?
       non_filtering_params = %i[
         scope state sort group_id include_subgroups
-        attempt_group_search_optimizations non_archived issue_types
+        attempt_group_search_optimizations attempt_full_text_search non_archived issue_types
       ]
 
       finder.params.except(*non_filtering_params).values.any?

spec/controllers/dashboard_controller_spec.rb

@@ -13,7 +13,22 @@ RSpec.describe DashboardController do
     end
 
     describe 'GET issues' do
-      it_behaves_like 'issuables list meta-data', :issue, :issues
+      context 'when issues_full_text_search is disabled' do
+        before do
+          stub_feature_flags(issues_full_text_search: false)
+        end
+
+        it_behaves_like 'issuables list meta-data', :issue, :issues
+      end
+
+      context 'when issues_full_text_search is enabled' do
+        before do
+          stub_feature_flags(issues_full_text_search: true)
+        end
+
+        it_behaves_like 'issuables list meta-data', :issue, :issues
+      end
+
       it_behaves_like 'issuables requiring filter', :issues
     end
 

spec/controllers/projects/issues_controller_spec.rb

@@ -72,7 +72,21 @@ RSpec.describe Projects::IssuesController do
         project.add_developer(user)
       end
 
-      it_behaves_like "issuables list meta-data", :issue
+      context 'when issues_full_text_search is disabled' do
+        before do
+          stub_feature_flags(issues_full_text_search: false)
+        end
+
+        it_behaves_like 'issuables list meta-data', :issue
+      end
+
+      context 'when issues_full_text_search is enabled' do
+        before do
+          stub_feature_flags(issues_full_text_search: true)
+        end
+
+        it_behaves_like 'issuables list meta-data', :issue
+      end
 
       it_behaves_like 'set sort order from user preference' do
         let(:sorting_param) { 'updated_asc' }

spec/features/issues/filtered_search/filter_issues_spec.rb

@@ -497,6 +497,8 @@ RSpec.describe 'Filter issues', :js do
       end
 
       it 'filters issues by searched text containing special characters' do
+        stub_feature_flags(issues_full_text_search: false)
+
         issue = create(:issue, project: project, author: user, title: "issue with !@\#{$%^&*()-+")
 
         search = '!@#{$%^&*()-+'

spec/finders/issues_finder_spec.rb

@@ -632,6 +632,29 @@ RSpec.describe IssuesFinder do
         end
       end
 
+      context 'filtering by issue term using full-text search' do
+        let(:params) { { search: search_term, attempt_full_text_search: true } }
+
+        let_it_be(:english) { create(:issue, project: project1, title: 'title', description: 'something english') }
+        let_it_be(:japanese) { create(:issue, project: project1, title: '日本語 title', description: 'another english description') }
+
+        context 'with latin search term' do
+          let(:search_term) { 'title english' }
+
+          it 'returns matching issues' do
+            expect(issues).to contain_exactly(english, japanese)
+          end
+        end
+
+        context 'with non-latin search term' do
+          let(:search_term) { '日本語' }
+
+          it 'returns matching issues' do
+            expect(issues).to contain_exactly(japanese)
+          end
+        end
+      end
+
       context 'filtering by issues iids' do
         let(:params) { { iids: [issue3.iid] } }
 

spec/models/concerns/pg_full_text_searchable_spec.rb

@@ -55,6 +55,34 @@ RSpec.describe PgFullTextSearchable do
     end
   end
 
+  describe '.pg_full_text_search' do
+    let(:english) { model_class.create!(title: 'title', description: 'something english') }
+    let(:with_accent) { model_class.create!(title: 'Jürgen', description: 'Ærøskøbing') }
+    let(:japanese) { model_class.create!(title: '日本語 title', description: 'another english description') }
+
+    before do
+      model_class.pg_full_text_searchable columns: [{ name: 'title', weight: 'A' }, { name: 'description', weight: 'B' }]
+
+      [english, with_accent, japanese].each(&:update_search_data!)
+    end
+
+    it 'searches across all fields' do
+      expect(model_class.pg_full_text_search('title english')).to contain_exactly(english, japanese)
+    end
+
+    it 'searches for exact term with quotes' do
+      expect(model_class.pg_full_text_search('"something english"')).to contain_exactly(english)
+    end
+
+    it 'ignores accents' do
+      expect(model_class.pg_full_text_search('jurgen')).to contain_exactly(with_accent)
+    end
+
+    it 'does not support searching by non-Latin characters' do
+      expect(model_class.pg_full_text_search('日本')).to be_empty
+    end
+  end
+
   describe '#update_search_data!' do
     let(:model) { model_class.create!(title: 'title', description: 'description') }