diff --git a/app/models/repository/git.rb b/app/models/repository/git.rb
index 0714b290b..1f0b168a4 100644
--- a/app/models/repository/git.rb
+++ b/app/models/repository/git.rb
@@ -66,9 +66,9 @@ def save_file_only(tmp_file, filepath, message, user)
 
   def commit_for!(commit_oid, pusher)
     instance = Commit.where(repository_id: self,
-                            commit_oid: commit_oid,
-                            pusher_id: pusher.try(:id),
-                            pusher_name: pusher.try(:name)).first_or_initialize
+                            commit_oid: commit_oid).
+      first_or_initialize(pusher_id: pusher.try(:id),
+                          pusher_name: pusher.try(:name))
     instance.fill_commit_instance! unless instance.persisted?
     instance
   end
diff --git a/doc/sidekiq_tips.md b/doc/sidekiq_tips.md
new file mode 100644
index 000000000..33d4c9b46
--- /dev/null
+++ b/doc/sidekiq_tips.md
@@ -0,0 +1,37 @@
+# Sidekiq Tips
+
+## Add job to queue other than specified in the Worker class
+You can add a job to a queue different from the one that is specified in the worker class.
+Instead of
+
+```ruby
+SomeWorker.perform_async(some, arguments)
+```
+
+you can execute
+
+```ruby
+Sidekiq::Client.push('queue' => 'some_other_queue',
+                     'class' => SomeWorker,
+                     'args' => [some, arguments])
+```
+This method accepts the following keys:
+* `queue` - the named queue to use, default `'default'`
+* `class` - the worker class to call, required
+* `args` - an array of simple arguments to the perform method, must be JSON-serializable
+* `retry` - whether to retry this job if it fails, `true` or `false`, default `true`
+* `backtrace` - whether to save any error backtrace, default `false`
+
+## Add many jobs to a queue
+To add tens of thousands of jobs to a queue, it is recommended to use
+```ruby
+Sidekiq::Client.push_bulk('queue' => 'some_other_queue',
+                          'class' => SomeWorker,
+                          'args' => [[some1, arguments1],
+                                     [some2, arguments2],
+                                     [some3, arguments3],
+                                     [some4, arguments4],
+                                     ])
+```
+It takes the same arguments as `push` above, but expects the `'args'` to be an array.
+It cuts down on the redis round trip latency.
diff --git a/lib/ontology_parsing_migration_worker.rb b/lib/ontology_parsing_migration_worker.rb
new file mode 100644
index 000000000..7994ea52a
--- /dev/null
+++ b/lib/ontology_parsing_migration_worker.rb
@@ -0,0 +1,3 @@
+class OntologyParsingMigrationWorker < OntologyParsingWorker
+  sidekiq_options queue: 'hets-migration'
+end
diff --git a/lib/tasks/ontology.rake b/lib/tasks/ontology.rake
new file mode 100644
index 000000000..8d6419582
--- /dev/null
+++ b/lib/tasks/ontology.rake
@@ -0,0 +1,25 @@
+namespace :ontology do
+  desc 'Reanalyze old ontologies'
+  task :reanalyze_all => :environment do
+    Ontology.where(parent_id: nil, present: true).order('updated_at desc').
+      find_each do |ontology|
+      if ontology.current_version.nil?
+        commit_oid = ontology.repository.git.get_file!(ontology.path).oid
+        ontology_version_options = OntologyVersionOptions.new(ontology.path,
+          User.where(admin: true).first)
+
+        OntologySaver.new(ontology.repository).
+          save_ontology(commit_oid, ontology_version_options)
+      else
+        OntologyParsingMigrationWorker.
+          perform_async([[ontology.current_version.id,
+            {fast_parse: false, files_to_parse_afterwards: []}, 1]])
+        Sidekiq::Client.push('queue' => 'hets-migration',
+                     'class' => OntologyParsingWorker,
+                     'args' => [[[ontology.current_version.id,
+                                  {fast_parse: false,
+                                   files_to_parse_afterwards: []}, 1]]])
+      end
+    end
+  end
+end
\ No newline at end of file