Merge branch 'trigram-index-searching' into 'master'

Refactor searching and use PostgreSQL trigram indexes for significantly
improved performance

Related issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/13743.

Also fixes #12410

See merge request !2987

3 files changed, 26 insertions, 19 deletions

diff --git a/lib/gitlab/project_search_results.rb b/lib/gitlab/project_search_results.rb
index 70de6a74e76..0607a8b9592 100644
--- a/lib/gitlab/project_search_results.rb
+++ b/lib/gitlab/project_search_results.rb
@@ -2,8 +2,8 @@ module Gitlab
   class ProjectSearchResults < SearchResults
     attr_reader :project, :repository_ref
 
-    def initialize(project_id, query, repository_ref = nil)
-      @project = Project.find(project_id)
+    def initialize(project, query, repository_ref = nil)
+      @project = project
       @repository_ref = if repository_ref.present?
                           repository_ref
                         else
@@ -73,7 +73,7 @@ module Gitlab
     end
 
     def notes
-      Note.where(project_id: limit_project_ids).user.search(query).order('updated_at DESC')
+      project.notes.user.search(query).order('updated_at DESC')
     end
 
     def commits
@@ -84,8 +84,8 @@ module Gitlab
       end
     end
 
-    def limit_project_ids
-      [project.id]
+    def project_ids_relation
+      project
     end
   end
 end
diff --git a/lib/gitlab/search_results.rb b/lib/gitlab/search_results.rb
index 2ab2d4af797..f13528a2eea 100644
--- a/lib/gitlab/search_results.rb
+++ b/lib/gitlab/search_results.rb
@@ -2,12 +2,12 @@ module Gitlab
   class SearchResults
     attr_reader :query
 
-    # Limit search results by passed project ids
+    # Limit search results by passed projects
     # It allows us to search only for projects user has access to
-    attr_reader :limit_project_ids
+    attr_reader :limit_projects
 
-    def initialize(limit_project_ids, query)
-      @limit_project_ids = limit_project_ids || Project.all
+    def initialize(limit_projects, query)
+      @limit_projects = limit_projects || Project.all
       @query = Shellwords.shellescape(query) if query.present?
     end
 
@@ -27,7 +27,8 @@ module Gitlab
     end
 
     def total_count
-      @total_count ||= projects_count + issues_count + merge_requests_count + milestones_count
+      @total_count ||= projects_count + issues_count + merge_requests_count +
+        milestones_count
     end
 
     def projects_count
@@ -53,27 +54,29 @@ module Gitlab
     private
 
     def projects
-      Project.where(id: limit_project_ids).search(query)
+      limit_projects.search(query)
     end
 
     def issues
-      issues = Issue.where(project_id: limit_project_ids)
+      issues = Issue.where(project_id: project_ids_relation)
+
       if query =~ /#(\d+)\z/
         issues = issues.where(iid: $1)
       else
         issues = issues.full_search(query)
       end
+
       issues.order('updated_at DESC')
     end
 
     def milestones
-      milestones = Milestone.where(project_id: limit_project_ids)
+      milestones = Milestone.where(project_id: project_ids_relation)
       milestones = milestones.search(query)
       milestones.order('updated_at DESC')
     end
 
     def merge_requests
-      merge_requests = MergeRequest.in_projects(limit_project_ids)
+      merge_requests = MergeRequest.in_projects(project_ids_relation)
       if query =~ /[#!](\d+)\z/
         merge_requests = merge_requests.where(iid: $1)
       else
@@ -89,5 +92,9 @@ module Gitlab
     def per_page
       20
     end
+
+    def project_ids_relation
+      limit_projects.select(:id).reorder(nil)
+    end
   end
 end
diff --git a/lib/gitlab/snippet_search_results.rb b/lib/gitlab/snippet_search_results.rb
index addda95be2b..e0e74ff8359 100644
--- a/lib/gitlab/snippet_search_results.rb
+++ b/lib/gitlab/snippet_search_results.rb
@@ -2,10 +2,10 @@ module Gitlab
   class SnippetSearchResults < SearchResults
     include SnippetsHelper
 
-    attr_reader :limit_snippet_ids
+    attr_reader :limit_snippets
 
-    def initialize(limit_snippet_ids, query)
-      @limit_snippet_ids = limit_snippet_ids
+    def initialize(limit_snippets, query)
+      @limit_snippets = limit_snippets
       @query = query
     end
 
@@ -35,11 +35,11 @@ module Gitlab
     private
 
     def snippet_titles
-      Snippet.where(id: limit_snippet_ids).search(query).order('updated_at DESC')
+      limit_snippets.search(query).order('updated_at DESC')
     end
 
     def snippet_blobs
-      Snippet.where(id: limit_snippet_ids).search_code(query).order('updated_at DESC')
+      limit_snippets.search_code(query).order('updated_at DESC')
     end
 
     def default_scope